23 mar 2014

TRANSCRIEREA genetic PK TRANSCRIEREA genetic PK + EK+ EK

TRADUCEREA informaTRADUCEREA informaiei geneticeiei genetice

CODUL GENETICCODUL GENETIC

Secia Biochimie anul II

EXPRESIAGENELOREXPRESIAGENELOR

Fluxul informaiei genetice

gen(ADN)

transcript primar(ARN)

transcrieregenetic

procesareatranscriptului

ARN ribozomal

ARN de transfer

ARN mesager

traducereainformatiei

genetice

ARN antisens

peptid

PrimaetapPrimaetapnexprimareagenelor=nexprimareagenelor=transcriereageneticagenelortranscriereageneticagenelor

Transcriere geneticTranscriere genetic

PrinTG

sesintetizeazatoatetipuriledeARNpropriicelulelor:ARNm,ARNr,ARNt,ARNhn

TG=procesuldesintez

amoleculelordeARN

caurmareacitiriiinformaieicodificat

nmoleculeleADN

DrumuldelaADN proteine

EstedefaptADN ARN proteine

TGestecatalizat

enzimatic

deenzimedenumite

TGseamncureplicarea,darsesintetizeazocatenARNinuADN;

deci,nmodsimilar,estecititocatenADN(=catenmatri),

iarcatenanouestesintetizeazpebazdecomplementaritatecumatria

ARNpolimerazeARNpolimeraze PK1speciemoleculardeARNpol/celul

EK3speciimolecularedeARNpol/celul

(TG)(TG)

moleculaARNrezultataprintranscriere,inaintedeoricealtaprocesaresenumestetranscriptprimartranscriptprimar

ncelule,ncelule,moleculeleARNsuntsintetizatepebazdecomplementaritatemoleculeleARNsuntsintetizatepebazdecomplementaritate,folosinddreptmatri,folosinddreptmatriocatenADNocatenADN

NucleotidepecatenaARNtranscriptNucleotidepecatenaARNtranscriptNucleotidepecatenaADNmatriNucleotidepecatenaADNmatri

CCGG

GGCC

AATT

UUAA

ncontrastcuADNpolimerazele,ncontrastcuADNpolimerazele,ARNpolimerazelenunecesitprimerARNpolimerazelenunecesitprimer,potata,potataaaiprimulnucleotiddepecatenanouiprimulnucleotiddepecatenanou

gen(ADN)

transcript primar(ARN)

transcrieregenetic

procesareatranscriptului

ARN ribozomal

ARN de transfer

ARN mesager

traducereainformatiei

genetice

ARN antisens

peptid

inhibarea transcrierii

TranscriereageneticsedesfTranscriereageneticsedesfoaroarnnbucladetranscrierebucladetranscriere

zonundedesfacedublulhelixADNzonundedesfacedublulhelixADN

55 33

bucldetranscrierebucldetranscriere ARNtranscriptARNtranscript

55

33 55

33

55 33

bucldetranscrierebucldetranscriere ARNtranscriptARNtranscript

55

33 55

33

55

33 5533

55 33

bucldetranscrierebucldetranscriere

ARNtranscriptARNtranscript

CatenaARNcesesiCatenaARNcesesinntetizeazprintranscrieretetizeazprintranscriere nurmneatanurmneataatlamatriatlamatriaADNpetoatlungimeaeiaADNpetoatlungimeaei,,cidoarpeunsegmentscurt,decidoarpeunsegmentscurt,de~15nucleotide~15nucleotide

restulmoleculeiARNrestulmoleculeiARNieseiese

dinhibridulARN:ADNdinhibridulARN:ADN

nansamblu,denansamblu,deiprocesuldetranscriereestesuficientdecorect(corectitudiniprocesuldetranscriereestesuficientdecorect(corectitudineasereferlacomplementaritateaeasereferlacomplementaritatea

ribonucleotidelordincatenaARNfaribonucleotidelordincatenaARNfadedeoxiribonucleotideledinmatridedeoxiribonucleotideledinmatriaADN),estetotuaADN),estetotuimaipuimaipuinin

acuratdectprocesuldereplicare.acuratdectprocesuldereplicare.

MecanismeledeMecanismeledeproofreadingproofreading

suntmaipusuntmaipuineficienteineficiententranscriere,comparativcureplicarentranscriere,comparativcureplicare

TranscriereTranscriere

1nucleotid1nucleotidgregreitit

/10.000nucleotide/10.000nucleotide

ReplicareReplicare

1nucleotid1nucleotidgregreitit

/10milioanenucleotide/10milioanenucleotide

nreplicareestecopiattotgenomulnreplicareestecopiattotgenomul

ntranscriereestecopiatinformantranscriereestecopiatinformaiadoardepeosingurcatenADNiadoardepeosingurcatenADN,,idoardinanumiteregiuniADN,denumitegeneidoardinanumiteregiuniADN,denumitegene

GenGen=r=regiunedinADNacreiinformaegiunedinADNacreiinformaieestecopiatieestecopiatnARNnARN

ORFORF==OpenReadingFrame=caOpenReadingFrame=cadrudeschiscitirii=zdrudeschiscitirii=zonADNceestetranscrisonADNceestetranscris

Ce regiuni din ADN se transcriu ? G E N G E N

Promotor G E N G E N Terminator

ARN p

ol

ARN p

ol

O zon din ADN cuprins ntre un promotor i un terminator = unitate de transcriereunitate de transcriere

Catena folosit ca matri ptr sinteza unui transcript este complementar cu el

i =

caten antisenscaten antisens

Catena ne-matri este denumit caten codificatoare sau caten senscaten sens

Zon din ADN creia i corespunde o copie ARNZon din ADN care codific pentru o protein / ARN

Promotor5

5

3

3

ARNpolARNpol

3

5transcriptARNtranscriptARN

catenaantisenscatenaantisens

5

5

3

3 rotomorP

ARNpolARNpol3 5

catenaantisenscatenaantisens

transcriptARNtranscriptARN

PeoaceeaPeoaceeaimoleculADNimoleculADN,u,unelegenesunttranscrisefolosindocatendreptmatrinelegenesunttranscrisefolosindocatendreptmatri,i,iaraltegenesunttranscrisearaltegenesunttranscrise

folosindcealaltcatenacamatrifolosindcealaltcatenacamatri..

AcestlucruestedeterminatdemodulAcestlucruestedeterminatdemodulncareseancareseaeazADNpolpemoleculaADNeazADNpolpemoleculaADN

ConvenConveniiinternaiiinternaionaledenotareionaledenotare

OriceregiuneADNdccusecvenOriceregiuneADNdccusecvencunoscutsepoatelistadoarpeosingurcatencunoscutsepoatelistadoarpeosingurcaten,,

cealaltfiindcunoscutprincomplementaritatecealaltfiindcunoscutprincomplementaritate

Maimultchiar,defoartemulteorinusemaiscriuMaimultchiar,defoartemulteorinusemaiscriuicifrele5icifrele5,3,3

Astfel,sescriedoarsecvenAstfel,sescriedoarsecvenacatenei5acatenei5 33,d,deex.:5eex.:5ATTGCCAATGGAATTGCCAATGGA33

PentrufiecareregiuneADNtranscrisPentrufiecareregiuneADNtranscris,n,nucleotidelesenumeroteazastfelucleotidelesenumeroteazastfel::

+1+1 PrimulnucleotiddincatenaADNmatriPrimulnucleotiddincatenaADNmatricareestecititcareestecititicreiaicreiaicorespundeprimulicorespundeprimul

nucleotidnucleotidntranscriptulARN;acestprimnucleotidcititmaiestenumitntranscriptulARN;acestprimnucleotidcititmaiestenumitiSITUSSTARTiSITUSSTART

+2...+n+2...+n UrmtoarelenucleotidedincatenaADNmatriUrmtoarelenucleotidedincatenaADNmatricititecitite,aflate,aflatenaval(naval(downstreamdownstream))

fafadeprimulnucleotidcititdeprimulnucleotidcitit

1...1...nn NucleotideledepecatenamatriNucleotideledepecatenamatriaflateaflatenamonte(namonte(upstreamupstream)fa)fadecadruldecitiredecadruldecitire,,

importanteptrgenaconsideratimportanteptrgenaconsiderat

+1+2+3+4+5 -1 -2 -3

+1 +2 +3 +4 +5-1-2-3-4

.....

.....

gena2

gena1situsSTART

(A)T(A)Transcrieremonocistronicranscrieremonocistronic

PP tgenaAgenaA

55 33

AA

ARNtranscriptARNtranscriptmonocistronicmonocistronic

transcrieretranscriere

traduceretraducere

unsingurunsingurpolipeptidpolipeptid

Ounitateadetranscriere=Ounitateadetranscriere=11gengen TranscrieremonocistronicTranscrieremonocistronic

3355

(B)T(B)Transcriereranscrierepolipolicistroniccistronic

PP tgenagenaBB genagenaDDggenaena

CC

transcrieretranscriere

traduceretraducere

ARNtranscriptARNtranscriptpolicistronicpolicistronic

BB CC DDmaimultepolipeptidemaimultepolipeptide

Ounitateadetranscriere=Ounitateadetranscriere=maimultemaimulte

gengenee TranscriereTranscrierepolipolicistroniccistronic

LaEK,majoritateageneloraupromotorpropriuLaEK,majoritateageneloraupromotorpropriuisunttranscriseisunttranscrisenunitnunitidistincte,procesulfiinddenumitidistincte,procesulfiinddenumittranscrieremonocistronictranscrieremonocistronic

LaPK,unelegene(maialescelereglatoare)aupromotorpropiuLaPK,unelegene(maialescelereglatoare)aupromotorpropiu

isunttranscriseprinTmonocistronicisunttranscriseprinTmonocistronic;;foartemultegenefoartemultegenensns,nuauPpropriu,cisuntcotranscriseprin,nuauPpropriu,cisuntcotranscriseprintranscrierepolicistronictranscrierepolicistronic

ARNpolimerazeARNpolimeraze

=e=enzimecesintetizeazmoleculeARNnzimecesintetizeazmoleculeARN,p,prinformarealegturilorfosfodiestericerinformarealegturilorfosfodiestericentreribonucleotide,ntreribonucleotide,ndirecndirecie5ie5 33

PK PK

1s1singurspeciemoleculardeARNpolimerazingurspeciemoleculardeARNpolimeraz ~~7000mole7000molecule/cecule/celullul

SintetiSintetizzeaeazz

toatetoate

speciilemolecularedeARNcelular:mesager(ARNm),ribozomal(speciilemolecularedeARNcelular:mesager(ARNm),ribozomal(ARNr),detransfer(ARNt)etcARNr),detransfer(ARNt)etc

EsteformatdinEsteformatdin4t4tipuridesubunitipuridesubuniti,i,codificatedegenediferite,cuformucodificatedegenediferite,cuformulagenerallageneral::22 (alpha)(alpha)

SpredeosebiredeADNpolimeraze,ARNpolimerazeleSpredeosebiredeADNpolimeraze,ARNpolimerazeleNUNUnecesitprimernecesitprimer

potatapotataaaiprimulnucleotidiprimulnucleotid

asamblareasubunitasamblareasubunitilorARNpolimerazeiilorARNpolimerazei

SeataSeataeazlamoleculaADNeazlamoleculaADN,lasecven,lasecvenedetipPROMOTORedetipPROMOTOR

seataseataeazlaregiuneaUPdinpromotorieazlaregiuneaUPdinpromotori((CTD)CTD)funcfuncioneazcadimerioneazcadimer

((beta)beta)

afinitatechimicptrADNafinitatechimicptrADN,seata,seataeazsituseazsitusnespecificnespecific

((betaprim)betaprim)formarealegturilorfosfoformarealegturilorfosfodiestericedintreribonucleotidediestericedintreribonucleotide

(sigma)(sigma)recunoarecunoatespecificregiunilepromotortespecificregiunilepromotoriseataiseataeazlaeleeazlaeledesfacedublulhelixADN,desfacedublulhelixADN,frintervenfrinterveniahelicazeiiahelicazei

dupterminareafazeideinidupterminareafazeideiniiereatranscrierii,seiereatranscrierii,sedesprindedesprinde,,

iarrestulsubunitiarrestulsubunitilordesfailordesfaoarelongareaoarelongareaiterminareatranscrieriiiterminareatranscrierii

==CTDCTDlinkerflexibillinkerflexibilNTDNTD

ARNpolimerazadelaPKARNpolimerazadelaPK

EtapeletranscrieriigeneticelaPK

IniIniiereatranscrieriilaPKiereatranscrieriilaPK

ncepedelaregiuninumitePROMOTORIncepedelaregiuninumitePROMOTORIcontinucontinuisedesfisedesfoarperegiunideschisecitiriioarperegiunideschisecitiriiseterminseterminnregiuninumiteTERMINATORInregiuninumiteTERMINATORI

Latoatetipuriledeorganisme,uncicludetranscriereesteforLatoatetipuriledeorganisme,uncicludetranscriereesteformatdin3etape:inimatdin3etape:iniiere,elongare,terminareiere,elongare,terminare

Regiunilepromotor=regiuniundeataRegiunilepromotor=regiuniundeataeazARNpolimerazeleeazARNpolimerazelei,respectiv,i,respectiv,

StructurapromotorilorlaPKincludesecvenStructurapromotorilorlaPKincludesecveneconsensus,econsensus,recunoscutedesubunitrecunoscutedesubunitialeARNpolimerazelorialeARNpolimerazelor

55TTGACATTGACA33 55TATAATTATAAT33UPUP //

StartStartHexamerulHexamerul3535 HexamerulHexamerul1010SitusulUPSitusulUP

151520b20b 5510b10b303060b60b

StructurapromotorilorlaPKStructurapromotorilorlaPK

LaPKsecvenLaPKsecveneleconsensusrecunoscutedesubuniteleconsensusrecunoscutedesubunitialeARNpolsunt:ialeARNpolsunt:

undearelocdeschidereadubluluihelixADNundearelocdeschidereadubluluihelixADNundeseformeazbucladetranscriereundeseformeazbucladetranscriere

hexamerulhexamerul35=osecven35=osecvenhexamerichexameric(forma(formatdintdin6p6pb)b)localizatlocalizatnpozinpoziiaia3535

hexamerulhexamerul10=osecven10=osecvenhexamerichexameric(forma(formatdintdin6p6pb)b)localizatlocalizatnpozinpoziiaia1010

TTGACATTGACA

TATAATTATAAT

situsulUP=osecvensitusulUP=osecvendede~~20pb20pb,c,culocalizarevariabilulocalizarevariabil40...40...80pbdesitusul+180pbdesitusul+1

recunoscutderecunoscutderecunoscutderecunoscutde

recunoscutderecunoscutdeCTDCTD

AttlaPK,ctAttlaPK,ctilaEK,uncicludeTGilaEK,uncicludeTG

SSchemaARNpolimerazeidelaprocariotechemaARNpolimerazeidelaprocarioteiataiataareaarea

acesteialaregiunipromotoracesteialaregiunipromotor

PromotorPromotornchisnchis

II

/Promotor/PromotornchisII/PromotordeschisnchisII/PromotordeschisLaPK,iniLaPK,iniiereatranscrieriisedesfiereatranscrieriisedesfoaroarn3stadii:n3stadii:

PromotorPromotornchisInchisII.ARNpolimeraza,respectiv,subunitateaI.ARNpolimeraza,respectiv,subunitatea,seata,seataeazlahexameruleazlahexamerul3535

II.ARNpolseaII.ARNpolseaeazpeADNeazpeADN,cuprinzndu,cuprinzndul;seatal;seataeazeazilahexilahex1010

PromotorPromotornchisIInchisII

Caurmare,ADNCaurmare,ADNulestecurbatulestecurbatitorsionatitorsionatntrecei2hexamerintrecei2hexameri

Darcei2hexamerinusuntorientaDarcei2hexamerinusuntorientaioptimfaioptimfadesitusuriledeatadesitusuriledeataarelaarelaPtraseataPtraseataastabillacei2hexameri,astabillacei2hexameri,distorsioneazmoleculaADNdistorsioneazmoleculaADN

DupsintezaaDupsintezaa8810ribonucleotide,10ribonucleotide,sedesprindedincomplexsedesprindedincomplex,m,miezulenzimeiARNpolimerazdesfiezulenzimeiARNpolimerazdesfoaroarnn

continuaresingurreaccontinuaresingurreaciadepolimerizare,iadepolimerizare,cuformarealegturilorfosfodiestericedintreribonucleotidecuformarealegturilorfosfodiestericedintreribonucleotide..

Laorganismeleprocariote,primulribonucleotidataLaorganismeleprocariote,primulribonucleotidataatatntranscriptesteATP/GTPntranscriptesteATP/GTP

PromotordeschisPromotordeschis

III.TIII.Tensiuneatorsionalesteeliberatprindeschidereadubluluihelensiuneatorsionalesteeliberatprindeschidereadubluluihelix,ix,

151520pb,20pb,regiunececuprinderegiunececuprindeisitusulstart+1;isitusulstart+1;seformeazastfelseformeazastfelbucladetranscrierebucladetranscriere

ElongaretrasncrieriilaPKElongaretrasncrieriilaPK

ntranscriereamultorgenedelantranscriereamultorgenedelaPKPK,,netapadeelonganetapadeelongarreparticipunsetdeproteinecuroldefactorideeparticipunsetdeproteinecuroldefactoride

elongaelongaieie,dintrecarecelmaiimportantesteproteinaNusG,carecre,dintrecarecelmaiimportantesteproteinaNusG,carecreteprocesivitateaARNpolimerazei(rolteprocesivitateaARNpolimerazei(rol

similarcucelalpeptiduluisimilarcucelalpeptidului

slidingclampslidingclamp

nprocesuldereplicare).nprocesuldereplicare).

MoleculadeARNcreMoleculadeARNcretetendirecndireciaia

55 33,reac,reaciafiindcatalizatdesubunitateaiafiindcatalizatdesubunitatea

bucladetranscrieresedeplaseazpemoleculadeADNbucladetranscrieresedeplaseazpemoleculadeADN

transcriptulARNnuestementranscriptulARNnuestemeninutinutnhibridpetoatlungimeanhibridpetoatlungimealuilui,cidoarpeaprox.,cidoarpeaprox.12b12b

DupceARNpolatrecutderegiuneaDupceARNpolatrecutderegiuneapromotorpromotor,acestase,acestasenchide,iarlaelsepoateatanchide,iarlaelsepoateataaoaltmoleculdeARNpolaoaltmoleculdeARNpol

ARNpoldelaARNpoldelaE.coliE.coliareoratdepolimerizaredeaproxareoratdepolimerizaredeaprox.3.30040nu40nucleotide/secuncleotide/secundladla37oC37oC

,prin2mecanisme:,prin2mecanisme:readingreadingproofproofiactivitatedeiactivitatedeoaroarARNpoldelaPKdesfARNpoldelaPKdesf,,adeelongareadeelongarezznfanfa

pirofosforoliticpirofosforoliticeditareeditare :ARNpol:ARNpolndeprteazunribonucleotidndeprteazunribonucleotidncorporatincorectncorporatincorect

hidrolitichidroliticeditareeditare :A:ARNpolsedeplaseazRNpolsedeplaseaznapoipetranscriptcuunulsaumaimultenapoipetranscriptcuunulsaumaimulte

ribonucleotide,taieoporribonucleotide,taieoporiunedetranscript,iunedetranscript,ndeprteazregiuneacundeprteazregiuneacu

eroareeroareireiaapoiprocesuldesintezireiaapoiprocesuldesintez;;naceastreacnaceastreacie,Aie,ARNpolesteRNpoleste

asistatdeproteinaasistatdeproteina GreGre

NusGNusG

bucl de transcriere

ARN transcript5

3

5

5

5

3

3

3

5

3

ARN transcript

ADN

ADN

bucla de transcriere se deplaseaz pe ADN

bucla de transcriere se nchide,iar transcriptul ARN este expulzat

4410ad10adenine,cefenine,ceformeazunaormeazunaaanumitsemnaldeterminarnumitsemnaldeterminare;e;

TerminareatranscrieriilaPKTerminareatranscrieriilaPK

..terminatorterminatoritranscriepnajungeinregiuneaunuiitranscriepnajungeinregiuneaunuiARNpolimerazasedeplaseazpemoleculaADNARNpolimerazasedeplaseazpemoleculaADN

SeconstatdecicSeconstatdecic,de,deiregiunileterminatorsuntdefinitepemoleculaADN,funciregiunileterminatorsuntdefinitepemoleculaADN,funciadeterminareatranscrieriioiadeterminareatranscrieriio

aretranscriptulARNaretranscriptulARN

2c2copiipoliopiipoliGCrepetateinvers,GCrepetateinvers,ceprezintcomplementaritateintracatenarceprezintcomplementaritateintracatenar

nmoleculadenmoleculadeARNARN

regiuneregiuneaformatdinceleaformatdincele2copiipoli2copiipoliGCGC ostructurostructurnacnacdedeprpr((hairpinhairpin))

transcriptulesteexpulzatdinbucladetranscrieretranscriptulesteexpulzatdinbucladetranscriere

buclabucla

sesenchidenchide

ARNpolimerazasedeprindedepemoleculaADNARNpolimerazasedeprindedepemoleculaADN

OsecvenOsecvenADNdetipterminatoresteformatdinADNdetipterminatoresteformatdin::

legturiledelegturiledeHH

dintredintreAdepematriAdepematriaADNaADN

iiUU

depetranscriptulARNsuntextremdeslabedepetranscriptulARNsuntextremdeslabe

careblocheazcareblocheaznaintareaARNpolnaintareaARNpol

LegturiledeHdinregiuneahibridALegturiledeHdinregiuneahibridA...Usuntinstabile...Usuntinstabile

ARNpolstaARNpolstaioneazioneaz

ii

nacestmodesteterminattranscriereageneticnacestmodesteterminattranscriereagenetic

complementaritateaintracatenaresteperfectcomplementaritateaintracatenaresteperfect

FuncFunciedegraduldecomplementaritateintracatenariedegraduldecomplementaritateintracatenar,,laPKlaPKaufostdescrisedouclasedeterminatoriaufostdescrisedouclasedeterminatori

::

structurastructurahairpinhairpinesteinstabilesteinstabil stabilizatstabilizatdede proteinaRhoproteinaRho(de(delaliteragreceasclaliteragreceasc

))terminatoriRhoterminatoriRhodependendependenii

terminatoriRhoterminatoriRhoindependenindependenii structurastructurahairpinhairpinestestabilfrintervenestestabilfrinterveniavreuneiproteineiavreuneiproteine

U U U U U U U 3

G C

G

G

G

G

G

G

C

C

C

C

C

C

5 ..

...

...

...

...

.........

StrucStructurturnacnacdedeprpr,curol,curolnnterminareatranscrieriigeneticeterminareatranscrieriigenetice

U U U U U U U 3

G C

G

G

G

G

G

G

C

C

C

C

C

C

5 ..

...

...

...

...

.........

U U U U U U U 3

G C

G

G

G

G

G

G

C

C

C

C

C

C

5 .. U U U U U U U 3

G C

G

G

G

G

G

G

C

C

C

C

C

C

5 ..

......

......

......

......

..................

StrucStructurturnacnacdedeprpr,curol,curolnnterminareatranscrieriigeneticeterminareatranscrieriigenetice

celedoucopiipoliceledoucopiipoliGCnuprezintocomplementaritateintracatenarperfectGCnuprezintocomplementaritateintracatenarperfect

U U U U U U U 3

G C

G

G

A

G

G

G

C

C

C

C

U

C

5 ..

..

...

...

...

........

ProteinaRhoProteinaRho

U U U U U U U 3

G C

G

G

A

G

G

G

C

C

C

C

U

C

5 ..

..

...

...

...

........

U U U U U U U 3

G C

G

G

A

G

G

G

C

C

C

C

U

C

5 .. U U U U U U U 3

G C

G

G

A

G

G

G

C

C

C

C

U

C

5 ..

....

......

......

......

................

ProteinaRhoProteinaRho

TRANSCRIEREATRANSCRIEREA

GENETICLAEKGENETICLAEK

nfiecarecelulEKexistcelpunfiecarecelulEKexistcelpuin3speciimolecularedeARNpolcetranscriutipuridiferitedin3speciimolecularedeARNpolcetranscriutipuridiferitedegeneegene

nafardeARNpolnafardeARNpol,,ntranscrierealaEKintervinmultealteproteinedenumitefactontranscrierealaEKintervinmultealteproteinedenumitefactoridetranscriere=TFridetranscriere=TF

nmajoritateaproceselordetranscrierenmajoritateaproceselordetranscriereioneazioneazdetranscriere(GTF)funcdetranscriere(GTF)funcgeneraligeneraliFactoriiFactorii

ntranscriereaanumitorgenentranscriereaanumitorgeneioneazdoarioneazdoardetranscriere(STF)funcdetranscriere(STF)funcspecificispecificiFactoriiFactorii

ProduProdussLocalizareLocalizareDenumireDenumire

ARNARNriboribozzomalomal

ARNr28S,18S,5,8SARNr28S,18S,5,8SnucleolnucleolARNpolIARNpolI

(PolI,PolA)(PolI,PolA)

AARNmesagerRNmesager

ARNmARNmMajoritateaARNnuclearmicMajoritateaARNnuclearmic

ARNsnARNsnARNdeinterferenARNdeinterferen

ARNiARNimicroARNmicroARN

ARNmiARNmi

nucleunucleuARNpolIIARNpolII

(PolII,PolB)(PolII,PolB)

ARNdetransferARNdetransfer

ARNtARNtARNribozomal5SARNribozomal5S

ARNr5SARNr5SUnelespeciimolecularedeARNmicUnelespeciimolecularedeARNmicARNsnU6,SRPARNARNsnU6,SRPARN

nucleunucleuii

interfainterfaanucleolanucleol

nucleunucleuARNpolIIIARNpolIII

(PolIII,PolC)(PolIII,PolC)

ARNpolimerazeledelaEKARNpolimerazeledelaEK nnucleuexistnnucleuexist3s3speciimolecularedeARNpol,cupeciimolecularedeARNpol,custructurstructurifuncifunciidiferiteiidiferite

LaplanteaufostdescriseLaplanteaufostdescrisencnc22speciimolecularedespeciimolecularedeARNpolimerazeARNpolimeraze

ARNpolIVARNpolIV,ARNpolV,ARNpolV

ARNiARNi

ARNpolIARNpolI TranscrietoategeneleptrARNr,cuexcepTranscrietoategeneleptrARNr,cuexcepiagenelorptrARN5SiagenelorptrARN5SGeneleptrARNrsuntorganizateGeneleptrARNrsuntorganizatentrntrosingurunitatedetranscriereosingurunitatedetranscriere

TranscrierepolicistronicTranscrierepolicistronic unsingurARNtranscriptconunsingurARNtranscriptconineinformaineinformaiadelamaimultegeneiadelamaimultegene

ARNprecursoresteprocesatARNprecursoresteprocesat 3moleculeArn:ARN18S,5,8S,28S3moleculeArn:ARN18S,5,8S,28S

TranscriereagenelorptrARNrarelocTranscriereagenelorptrARNrarelocnnucleol,undeapoiARNrestecombinatcuproteineribozomalennucleol,undeapoiARNrestecombinatcuproteineribozomale ribozomiribozomi

ARNpolIIARNpolII TranscrietoategeneleptrARNmTranscrietoategeneleptrARNmTranscrieTranscrieiunelegeneptrARNsn,ARNsiiunelegeneptrARNsn,ARNsiitoateARNmiitoateARNmi

TranscrieremonocistronicTranscrieremonocistronic unARNtranscriptcomunARNtranscriptcomineinfomaineinfomaiadelaosingurgeniadelaosingurgen

ARNtranscript=ARNpreARNtranscript=ARNpremesagermesager esteprocesatesteprocesat ARNmieseprinporiimembraneinucleareARNmieseprinporiimembraneinuclearencitoplasmncitoplasm

ARNpolIIIARNpolIII TranscrietoategeneleptrARNtTranscrietoategeneleptrARNtTranscrieTranscrieigeneleptrARNr5S,ARNsnU6,SRPARN,ARNTERigeneleptrARNr5S,ARNsnU6,SRPARN,ARNTER

Toatecele3ARNToatecele3ARNpoldelaEKaustructurcomplexpoldelaEKaustructurcomplex,fiindformatedin14,12,fiindformatedin14,12i,i,respectiv,17subunrespectiv,17subunititi,i,dincaredincare

unelesuntsimilarecusubunitunelesuntsimilarecusubunitileARNpolPKileARNpolPK

StructurapromotorilorlaEKStructurapromotorilorlaEK

maimaintiseatantiseataeazTFlaPeazTFlaP,iaracestcomplexesteapoirecunoscutdeARNpolimeraze,iaracestcomplexesteapoirecunoscutdeARNpolimeraze

Fiecaredincele3ARNpolimerazerecunoscTFdiferiFiecaredincele3ARNpolimerazerecunoscTFdiferiicareseataicareseataeazlaPcustructurdiferiteazlaPcustructurdiferit

majoritateapromotorilorptrARNpolImajoritateapromotorilorptrARNpolIiIIsuntupstreamfaiIIsuntupstreamfadesitusulstartdesitusulstart

promotoriiptrARNpolIIIaumultemoduledownstreamfapromotoriiptrARNpolIIIaumultemoduledownstreamfadestartdestart

LaEK,LaEK,promotoriiaustructurmultipromotoriiaustructurmultimodularmodularisuntregiunimultmaicomplexedectPdelaPKisuntregiunimultmaicomplexedectPdelaPK

LaEK,nuARNpolimerazelerecunoscpromotorii(P),cifactoriiLaEK,nuARNpolimerazelerecunoscpromotorii(P),cifactoriidetranscriere(TF):detranscriere(TF):

FactoriidetranscrieresenoteazdiferitFactoriidetranscrieresenoteazdiferit,func,funciedeARNpolimeraziedeARNpolimeraz::

ARNpolIrecunoaARNpolIrecunoateclasaI=TFIteclasaI=TFI

ARNpolIIrecunoaARNpolIIrecunoateclasaII=TFIIteclasaII=TFII

ARNpolIIIrecunoaARNpolIIIrecunoateclasaIII=TFIIIteclasaIII=TFIII

Promotoriiptrcele3ARNpoliPromotoriiptrcele3ARNpolimerazedifernudoarcastructurmerazedifernudoarcastructur,ci,ciicalocalizarefaicalocalizarefadegenadetranscrisdegenadetranscris::

StructuradebazaunuiPptrARNpolIIStructuradebazaunuiPptrARNpolII

Promotorulprimar(Promotorulprimar(corepromotercorepromoter)ptrARNpolII=80pb:)ptrARNpolII=80pb:40...+4040...+40arestructurmultiarestructurmultimodularmodular

lafiecaremodul/regiuneseatalafiecaremodul/regiuneseataeazunfactordetranscriereeazunfactordetranscriere

TFTFmajoritateamodulelorsuntupstreammajoritateamodulelorsuntupstream,d,darexistarexistiuneledownstreamiuneledownstreamexistexistiunmodulexactpestesitusulstartiunmodulexactpestesitusulstart

PtrcaosingurgensfietranscrisdeARNpolIIPtrcaosingurgensfietranscrisdeARNpolII,estenecesarcaseturi,estenecesarcaseturintregideproteine(factoridetranscrierentregideproteine(factoridetranscriereTFIITFII))

sseatasseataezelamultipleregiunidinADN:ezelamultipleregiunidinADN:

MajoritateagenelortranscrisedeARNpolIIaumaimulteregiunMajoritateagenelortranscrisedeARNpolIIaumaimulteregiunidetippromotor:idetippromotor:

regiunidetippromotorregiunidetippromotor

regiunicufuncregiunicufunciireglatorii(enhanceri,silenceri,insulatori)iireglatorii(enhanceri,silenceri,insulatori)vorfidiscutatevorfidiscutatenaltcursnaltcurspromotorprimarpromotorprimarpromotorproximalpromotorproximalpromotordistalpromotordistal

nesennesen,u,unPprimarptrARNpolIIesteformatdinurmtoareleregiuninPprimarptrARNpolIIesteformatdinurmtoareleregiuni/module:/module:

BREBRE TATATATA InrInr DCEIDCEI DCEIIDCEII DCEIIIDCEIII

+1+1

upstreamupstream downstreamdownstream

25253333 +5+5 +15+15 +30+30

PartedingeneletranscriseARNpolII,auPartedingeneletranscriseARNpolII,auostructurpuostructurpuindiferitindiferit

nlocdemodulTATAauDPEnlocdemodulTATAauDPE

BREBRE DPEDPEInrInr DCEIDCEI DCEIIDCEII DCEIIIDCEIII

+1+1

upstreamupstream downstreamdownstream

25252020 +5+5 +15+15 +30+30

PfrTATAPfrTATAPcuTATAPcuTATA

BREBREBREBRE

TATATATA

InrInrInrInr

DCEI,II,IIIDCEI,II,IIIDCEI,II,IIIDCEI,II,III

DPEDPE

SitusuriupstreamSitusuriupstream SitusuridownstreamSitusuridownstream

InrInr

SitusuriupstreamSitusuriupstream

TATATATA

BREBRE

SitusulSitusul

SitusuridownstreamSitusuridownstream

DCEI/II/IIIDCEI/II/III

DPEDPE

DownstreamPromoterElementDownstreamPromoterElement,l,laPfrTATAaPfrTATA

TFIIBRecognitionElementTFIIBRecognitionElement

=octamer(8pb),bogatinGC:=octamer(8pb),bogatinGC:GGGCGCCCGGGCGCCC

cutiaTATA=heptamer(7pb),bogatinAT:cutiaTATA=heptamer(7pb),bogatinAT:TATAAAA/TATTATAAAA/TAT

InrInr

Initiator:Initiator:YYCAYYYYYYYCAYYYYY((PyPy

22

CAPyCAPy

55

)),P,Py=y=oricepirimidinoricepirimidin,deobiceiA=nucleotidul+1,deobiceiA=nucleotidul+1

nafardePprimarnafardePprimar,c,cutoateregiunilelui,utoateregiunilelui,transcriereageneticlaEKesteinfluentranscriereageneticlaEKesteinfluenatatidealteregiuniADN:idealteregiuniADN:

PromotorulproximalPromotorulproximal

upstreamfaupstreamfadePprimardePprimar,la250pbdesitusulstart,la250pbdesitusulstart

conconineregiunireglatoriiprimareineregiunireglatoriiprimare

laacesteaseatalaacesteaseataeazfactoridetranscrierespecificieazfactoridetranscrierespecifici

PromotoruldistalPromotoruldistal

upstreamfaupstreamfadePprimardePprimar,la,la>>250pbdesitusulstart250pbdesitusulstart

conconineregiunireglatoriiineregiunireglatorii,darinfluen,darinfluenaestemaislabaestemaislabdectaPdistaldectaPdistal

laacesteaseatalaacesteaseataeaztotfactoridetranscrierespecificieaztotfactoridetranscrierespecifici

=TranscriptionFactors=TF=TranscriptionFactors=TFFactoriidetranscriereFactoriidetranscriere

SuntproteinecustructurtipicptrataSuntproteinecustructurtipicptrataarelaADNarelaADNTemptrseminarTemptrseminar:clasestructuraledeTF:clasestructuraledeTF

SenoteazcuISenoteazcuI,II,IIiIII,funciIII,funciedeARNpolimerazapecareorecruteaziedeARNpolimerazapecareorecruteaz(ARNpolI,IIsauIII)(ARNpolI,IIsauIII)

DinpunctdevederefuncDinpunctdevederefuncionalseclasificionalseclasificn:n:

FactoridetranscriereGENERALIFactoridetranscriereGENERALI

GeneralTranscriptionFactors(GeneralTranscriptionFactors(GTFGTF

),seata),seataeazlaPprimareazlaPprimar

FactoridetranscriereSPECIFICIFactoridetranscriereSPECIFICI

SpecificTranscriptionFactors(SpecificTranscriptionFactors(STFSTF

),seata),seataeazlaPproximaleazlaPproximalilaceldistalilaceldistal

GTFGTF

secveneleInr,DCE,DPEInr,DCE,DPE

secvena

BREBRE=TFIIBrecognitionelement

TFIIDTFIID

TFIIBTFIIB

TFIIBTFIIB TBPTBP

TFIIDTFIID

FactoriigeneralidetranscriereptrARNpolIIsunt:TBP,TFIIFactoriigeneralidetranscriereptrARNpolIIsunt:TBP,TFIIB,TFIID,TFIIA,TFIIF,TFIIEB,TFIID,TFIIA,TFIIF,TFIIEiTFIIHiTFIIH

DoarDoarTFIIDTFIID

iiTFIIBTFIIBseleaglamoleculaADNseleaglamoleculaADN(laregiunilespecificedinPprimar);(laregiunilespecificedinPprimar);

restulseleaglaTFIIDsaulaTFIIBsaulaARNpolIIrestulseleaglaTFIIDsaulaTFIIBsaulaARNpolII

=TAFs=TBP=TAFs=TBPAssociatedFactorsAssociatedFactors

TAFTAFTAFTAFTAFTAFTAFTAFTAFTAF

TBPTBP =TATAbindingprotein secvenaTATATATA

EtapeletranscrieriigeneticelaEKEtapeletranscrieriigeneticelaEK

PrePreiniiniiereiere

ataataareafactorilorgeneralidetranscriereGTFlaPprimarareafactorilorgeneralidetranscriereGTFlaPprimar iereierecomplexuluidepreinicomplexuluidepreiniformareaformarea

formareaacestuicomplexformareaacestuicomplexncepedelaelementulTATAncepedelaelementulTATA==

setulcompletdeGTFsetulcompletdeGTFARNpolARNpol

ataataareaGTFslaPprimararelocareaGTFslaPprimararelocntrntroanumitordineoanumitordine

semnalulptratasemnalulptrataareaareancascadacelorlalteproteinencascadacelorlalteproteine

TFIIBstabilizeazcomplexulTBPTFIIBstabilizeazcomplexulTBPTATATATAirecruteazARNpolIIirecruteazARNpolII

TFIIFfacelegturadintreTBPataTFIIFfacelegturadintreTBPataatlaTATAatlaTATAiARNpoliARNpol

activitateATPazicactivitateATPazic(ptrdesfaceread.h.(ptrdesfaceread.h.iformareabucleidetranscriere)iformareabucleidetranscriere)

TFIITFIIEErecruteazTFIIHrecruteazTFIIH

PrePreiniiniiere,Iniiere,Iniiere,Elongare,Terminareiere,Elongare,Terminare

activitateproteinkinazicactivitateproteinkinazic(ptr(ptrfosforilareacaptuluiCalARNpolIIfosforilareacaptuluiCalARNpolII))TFIIHareTFIIHare

1.1.

ARNpolIIARNpolII

TBPTBP TATATATA

TFIIDTFIID TAFTAF

TFIIBTFIIB BREBRE2.2.

MoleculaADNseMoleculaADNsendoaiecu80ndoaiecu80oo

==

3.3. InrInr

4.4. TFIIDTFIID TAFTAF DCEI,II,IIIDCEI,II,III

5.5. ++TFIIFTFIIF TBPTBP

6.6. TFIITFIIEE ARNpolIIARNpolII

7.7. TFIIHTFIIH ARNpolIIARNpolII

TFIIDTFIIDTBPTBPTFIIBTFIIBTFIIDTFIIDTAFTAFARNpolIIARNpolIITFIITFIIA,A,F,E,HF,E,H

ComplexuldepreiniComplexuldepreiniiereiere

DesfacereadubluluihelixADNDesfacereadubluluihelixADN

FormareabucleidetranscriereFormareabucleidetranscriere

ProcesulemediatdeTFIIHcuhidrolizATPProcesulemediatdeTFIIHcuhidrolizATPIniIniiereiere ==FormareabucleidetranscriereFormareabucleidetranscriere

AtaAtaareaprimelorribonucleotideareaprimelorribonucleotide

ntranscriptulARNntranscriptulARN

DatoritfaptuluicmoleculaADNestecomplexatcuhistoneDatoritfaptuluicmoleculaADNestecomplexatcuhistone((nucleozomi),nucleozomi),complexmediatorcomplexmediatoriaaltorproteine=iaaltorproteine=iinterveniinterveniereatranscrieriigeneticenecesitiereatranscrieriigeneticenecesitierea/iniierea/iniiniiniprepre

ElongareaElongareaaceastetapaceastetapncepeatuncicndARNpolprsencepeatuncicndARNpolprsetepromotorultepromotorul

latrecereadintreInilatrecereadintreIniiereiereiElongare,factoriidetranscrieresuntiElongare,factoriidetranscrieresuntnlocuinlocuiicualteproteine:icualteproteine:

TFIISTFIIS

arerolarerolnactivitateadenactivitateadeproofproofreadingreading

aARNpol,similarcuproteinaGredelaPKaARNpol,similarcuproteinaGredelaPK

SPT5SPT5=unEFsimilarcuNusGdelaPK=unEFsimilarcuNusGdelaPK

NusG/SPT5=singurulTFconservatuniversallatoatecele3domeNusG/SPT5=singurulTFconservatuniversallatoatecele3domeniinii

Bacteria,Archaea,EukaryaBacteria,Archaea,Eukarya

arerolarerolnprocesivitateaARNpolII,similarcunprocesivitateaARNpolII,similarcuslidingclampslidingclamp

FACTORIDEELONGARE(EF)FACTORIDEELONGARE(EF)

ProteinedeDEZASAMBLARE/ASAMBLAREaNUCLEOZOMILORProteinedeDEZASAMBLARE/ASAMBLAREaNUCLEOZOMILOR

FACTFACT FacilitatesChromatinTranscriptionFacilitatesChromatinTranscriptiondezasambleaznucleozomiidezasambleaznucleozomiinfanfaaARNpolimerazeiII,aARNpolimerazeiII,ptrcaaceastaspoattranscrieptrcaaceastaspoattranscrie

asambleaznucleozomiiasambleaznucleozomiinzoneledejatranscrisenzoneledejatranscrise

FACTFACT

FACTFACT

ARNtranscriptARNtranscript

ProteinedePROCESAREaTRANSCRIPTULUIProteinedePROCESAREaTRANSCRIPTULUI

DaclaPKDaclaPK,traducereaARNtranscript,traducereaARNtranscriptncepechiarncepechiarntimpceacestaestesintetizat,laEKtranscriptulARNestentimpceacestaestesintetizat,laEKtranscriptulARNeste

procesatprocesatnaintedeafitradus.naintedeafitradus.

==alARNalARN55adugareauneiguaninemetilatelacapuladugareauneiguaninemetilatelacapulUnprimmecanismdeprocesareatranscriptului=Unprimmecanismdeprocesareatranscriptului=I.I.

enzimacarerealizeaztransferuluneiguaninemetilateenzimacarerealizeaztransferuluneiguaninemetilate==aceastenzimseataaceastenzimseataeazinieaziniialladomeniulcarboxiialladomeniulcarboxiterminalalARNpolimerazei,terminalalARNpolimerazei,

guanililguanililtransferazatransferaza

apoienzimaseataapoienzimaseataeazlacapuleazlacapul55

altranscriptuluialtranscriptuluiirealizeaztransferuluneiGmetilateirealizeaztransferuluneiGmetilate

alARNalARN(A)lacapul3(A)lacapul3adugareacoziipoliadugareacoziipoli==Cronologic,unaldoileamecanismdeprocesareatranscriptuluiCronologic,unaldoileamecanismdeprocesareatranscriptuluiII.II.

procesulareloclaterminareatranscrierii,darpartedinprotprocesulareloclaterminareatranscrierii,darpartedinproteinelenecesareseataeinelenecesareseataeazlaARNpolIIeazlaARNpolIInfazadeelongarenfazadeelongare

CAPPINGCAPPING

PT=proteinacetaieARNPT=proteinacetaieARNPAP=pPAP=proteinaceadaugroteinaceadaug~~200ade200adenine=ponine=poliliAApolimerazpolimeraz

proteinacareseataproteinacareseataeazeaznfazadeelongare=proteinacetaieARN=nfazadeelongare=proteinacetaieARN= PTPT

ARNARN

procesularelocprocesularelocntimpulfazeideelongareatranscrieriintimpulfazeideelongareatranscrierii

((ProcesareTranscriptProcesareTranscript))

ARNARN

AtaAtaareaproteinelordeprocesareatranscriptuluilaARNpolIIareaproteinelordeprocesareatranscriptuluilaARNpolIInfazadeelongareatranscrieriinfazadeelongareatranscrierii

TerminareatranscrieriilaEKTerminareatranscrieriilaEK

LaEK,terminareatranscrieriiestedeclanLaEK,terminareatranscrieriiestedeclanatdeajungereaARNpolIIatdeajungereaARNpolIInregiuneadenumitnregiuneadenumitsecvensecvensemnalpolisemnalpoliAA::

proteinaPT(proteinaPT(ProcesareTranscriptProcesareTranscript)trecedepeARNpolIIpetranscriptulARN,)trecedepeARNpolIIpetranscriptulARN,nregiuneasemnalpolinregiuneasemnalpoliAdepeacestaAdepeacesta

proteinaPTcliveazmoleculaARNproteinaPTcliveazmoleculaARNnaceastregiunenaceastregiune

restulmoleculeiARN,cenuareMetrestulmoleculeiARN,cenuareMetGlacapul5Glacapul5,e,estedigeratdeoRNazstedigeratdeoRNaz

bucladetranscrieresebucladetranscrieresenchide,ARNpolIIsedesprindedepeADNnchide,ARNpolIIsedesprindedepeADN

(lageneletranscrisedeARNpolII)(lageneletranscrisedeARNpolII)

PROCESAREAARNmesagerPROCESAREAARNmesager

GenGen

ARNmesagerARNmesager

ProteinProtein

secvensecvencodificatoarecodificatoare

TranscrieregeneticTranscrieregenetic

TraduceregeneticTraduceregenetic

GenGen

ARNmesagerARNmesager

ProteinProtein

TranscrieregeneticTranscrieregenetic

TraduceregeneticTraduceregenetic

secvnecodifsecvnecodifsecvcodifsecvcodif secvcodifsecvcodif

mesagermesagerprepreARNARN

ProcesaretranscriptProcesaretranscript

PK PK EK EK

LaLaPKPK,traducereainforma,traducereainformaieigeneticeatranscriptuluiieigeneticeatranscriptului

ARNARNncepechiarncepechiarnaintedeterminareanaintedeterminarea

transcrieriitranscrierii

LaLaEKEK,transcriptulini,transcriptuliniialestemaiialestemaintiprocesat:ntiprocesat:

ApoiacestaiesedinnucleusprecitoplasmApoiacestaiesedinnucleusprecitoplasm

ncitoplasmncitoplasmncepetraducereainformancepetraducereainformaieigeneticeieigenetice

LaEK,traducereaLaEK,traducereaNUNUestesimultancutranscriereaestesimultancutranscriereaLaPKtraducereaestecvasiLaPKtraducereaestecvasisimultancutranscriereasimultancutranscrierea

ARNpreARNpremesagermesager ARNmesagerARNmesager

EtapeleprocesriitranscriptelorpreEtapeleprocesriitranscriptelorpremesagermesager

(GT)(GT)transferoguaninmetilatlacapultransferoguaninmetilatlacapul55

alARNalARN

GTseataGTseataeazinieaziniialladomeniulcarboxiialladomeniulcarboxiterminalalARNpolimerazei,terminalalARNpolimerazei,guanililguanililtransferazatransferaza

apoienzimaseataapoienzimaseataeazlacapuleazlacapul55

altranscriptuluialtranscriptuluiirealizeaztransferuluneiGmetilateirealizeaztransferuluneiGmetilate

ARNARN

ntimpulfazeideelongareatranscrieriintimpulfazeideelongareatranscrierii==adugareauneiguaninemetilatelacapuladugareauneiguaninemetilatelacapul55

alARNalARN1.1. CAPPINGCAPPING

adugareacoziipoliadugareacoziipoli(A)lacapul3(A)lacapul3

alARNalARN

procesulareloclaterminareatranscrierii,darpartedinprotprocesulareloclaterminareatranscrierii,darpartedinproteinelenecesareseataeinelenecesareseataeazlaARNpolIIeazlaARNpolIInfazadeelongarenfazadeelongare

proteinacareseataproteinacareseataeazeaznfazadeelongare=proteinacetaieARN=nfazadeelongare=proteinacetaieARN= PTPT ((ProcesareTranscriptProcesareTranscript))

2.2. CoadapoliCoadapoliAA

enzimaenzima

PT=proteinacetaieARNPT=proteinacetaieARN

PAPadaugPAPadaug~~200adenine200adenine

DupcetranscriptulestetiatdeproteinaPTDupcetranscriptulestetiatdeproteinaPT,,

seataseataeazproteinaeazproteinapolipoliApolimerazApolimeraz

(PAP)lacapul3(PAP)lacapul3

PAPPAP==oARNpolimerazspecialoARNpolimerazspecial

PemsurcePAPadaugadeninePemsurcePAPadaugadenine,,

lacoadapolilacoadapoliAseataAseataeaznieazniteproteinespecificeteproteinespecifice

PABPPABP(poly(polyABindingProtein)ABindingProtein)

3.3. SplicingSplicing

LaEK,LaEK,multegenececodificptrproteinesuntformatedinregiunicodmultegenececodificptrproteinesuntformatedinregiunicodificatoarecealterneazcuregiuninecodificatoareificatoarecealterneazcuregiuninecodificatoare

regiuninecodificatoare=regiuniADNcesunttranscrise,darnuregiuninecodificatoare=regiuniADNcesunttranscrise,darnu

sunttradusesunttraduse(nuauechivalent(nuauechivalentnsecvennsecvenadeaminoacizidinproteine)adeaminoacizidinproteine)

EXONIEXONI

regiunicodificatoare=regiuniADNcesunttranscriseregiunicodificatoare=regiuniADNcesunttranscriseiapoitraduseiapoitraduse

INTRONIINTRONI

(auechivalent(auechivalentnsecvennsecvenadeaminoacizidinproteine)adeaminoacizidinproteine)

ADNADN

ARNARNprepremesagermesager

ARNmesagerARNmesager

reg.codif.reg.codif. reg.codif.reg.codif. reg.codif.reg.codif. reg.codif.reg.codif. reg.codif.reg.codif.EXONEXON EXONEXONEXONEXON INTRONINTRONINTRONINTRON

EXONEXON EXONEXONEXONEXON INTRONINTRONINTRONINTRON

EXONEXONEXONEXONEXONEXON

TRANSCRIEREGENETICTRANSCRIEREGENETIC

TRADUCEREGENETICTRADUCEREGENETIC

ProteinProtein

SPLICINGSPLICING (eliminareaintronilor)(eliminareaintronilor)

mozaicatmozaicatAcestegeneaustructurAcestegeneaustructur

NumruldeintronipergenvariazdelagenlagenNumruldeintronipergenvariazdelagenlagen,delaspecielaspecie,delaspecielaspecie

idimensiuneaintronilorvariazidimensiuneaintronilorvariaz;uneori,introniisuntchiarmaimaridectexonii;uneori,introniisuntchiarmaimaridectexonii

Intronigrup1Intronigrup1

selfsplicingribozymeselfsplicingribozymeIntronigrup2Intronigrup2

spliceosomispliceosomi

snRNPssnRNPs

MecanismedesplicingMecanismedesplicing

SecvenSecvenedinARNpreedinARNpremesagerimplicatemesagerimplicatensplicingnsplicingulintronilordegrupIIulintronilordegrupII

GU.........................................A(Py)10..............GU.........................................A(Py)10..............AGAGexonexon intronintron

55

exonexon

situsul5situsul5

splicesplice situsul3situsul3

splicesplicesitusulsitusulbranchbranch

Dpdvchimic,spDpdvchimic,splicingulserealizeazlicingulserealizeaznmaimulteetape:nmaimulteetape:

1.Clivajlasitusul51.Clivajlasitusul5

splicesplice

2.Capul52.Capul5

alintronuluiseataalintronuluiseataeazprintransesterificarelaAdinsitusuleazprintransesterificarelaAdinsitusulbranchbranch

3.Clivajlasitusul33.Clivajlasitusul3

splicesplice

4.Capul34.Capul3OHalexonului1seataOHalexonului1seataeazlacapul5eazlacapul5OHalexonului2OHalexonului2

GU.........................................A(Py)GU.........................................A(Py)

1010

..............AG..............AGexon1exon1 intronintron

3355

exon2exon2

situsul3situsul3

splicesplicesitusulsitusulbranchbranch

33 55

exon1exon1

intronlariatintronlariat

3355exon2exon233 33 55

A(Py)A(Py)

1010 AGAGexon1exon1

55 33 33

exon2exon2

A(Py)A(Py)

1010 AGAGintronlariatintronlariat

exon1exon155 33

exon2exon2A(Py)A(Py)

1010 AGAG

ARNmesagerARNmesagerintronlariatintronlariat

SPLICEOSOMSPLICEOSOM==complexribonucleoproteic(RNP)ccomplexribonucleoproteic(RNP)cerealizeazeliminareaintronilordingrupulIIerealizeazeliminareaintronilordingrupulII=5RNP=5RNP

Cele5moleculeARN=ARNsn(smallnuclear=nuclearmic,100Cele5moleculeARN=ARNsn(smallnuclear=nuclearmic,100300b):U1,U2,U4,U5,U6300b):U1,U2,U4,U5,U6

U1U1+p+proteinrotein U1U1snRNPsnRNPU2U2+p+proteinrotein U2U2snRNPsnRNPU4U4+p+proteinrotein U4U4snRNPsnRNPU5U5+p+proteinrotein U5U5snRNPsnRNPU6U6+p+proteinrotein U6U6snRNPsnRNP

1RNP=1RNP=1p1proteinrotein1ARN1ARN

U1U1snRNPsnRNPU2U2snRNPsnRNP

U4U4snRNPsnRNPU5U5snRNPsnRNP

U6U6snRNPsnRNP

SPLICEOSOMSPLICEOSOM

U1U1snRNPsnRNP U2U2snRNPsnRNP

U4U4snRNPsnRNPU5U5snRNPsnRNPU6U6snRNP

snRNP

GU.........................................A(Py)10..............GU.........................................A(Py)10..............AGAGexon1exon1 intronintron

55

exon2exon2

situsul5situsul5

splicesplice situsul3situsul3

splicesplicesitusulsitusulbranchbranch

TRADUCEREAINFORMATRADUCEREAINFORMAIEIGENETICEIEIGENETICE=complexulproceselorbiochimiceprincareinforma=complexulproceselorbiochimiceprincareinformaiageneticreprezentatdeiageneticreprezentatde

secvensecvenadenucleotidedinARNmesagerestetradusadenucleotidedinARNmesagerestetradusnsecvennsecvendede

aminoaciziaminoacizinproteinenproteine

TraducereainformaTraducereainformaieigeneticeieigenetice

ARNmARNm Proteine Proteine traduceretraducere

Rezultatultranscrierii=ARNtranscriptprimarRezultatultranscrierii=ARNtranscriptprimar

Rezultatulsplicingului(laEK)=ARNmesager(matur)Rezultatulsplicingului(laEK)=ARNmesager(matur)

Rezultatultraducerii=proteineRezultatultraducerii=proteine

LatraducereainformaLatraducereainformaieigeneticeparticipmaimultetipuridemoleculeieigeneticeparticipmaimultetipuridemolecule::

conconineinformaineinformaiageneticcetrebuietradusiageneticcetrebuietradus

=ARNdetransfer,aduceaminoacizilaloculbiosintezeiproteic=ARNdetransfer,aduceaminoacizilaloculbiosintezeiproteicee

=organitecelulare,formatedinARNr=organitecelulare,formatedinARNriproteineribozomale,iproteineribozomale,mediazsintezaproteinelormediazsintezaproteinelor

ARNmARNm

ARNtARNt

ribozomiribozomi

ADNADNtranscrieretranscriere

ARNmARNmDoaroporDoaroporiunedinsecveniunedinsecvenaARNmestedecodificataARNmestedecodificatnsecvennsecvendeaminoacizideaminoaciziInformaInformaiaianARNmestetradusnARNmestetradusncepnddelacapul5ncepnddelacapul5 33,,nseturidecte3nucleotide=nseturidecte3nucleotide=CODONCODON

MultemoleculeARNmsuntpolicistronice(conMultemoleculeARNmsuntpolicistronice(conininformaininformaiedelamaimultegene)iedelamaimultegene)

RBS=ribosomeRBS=ribosomebindingsite=secvenbindingsite=secvenShineShineDalgarnoDalgarnoestecomplementarcuosecvenestecomplementarcuosecvendinARNrdinARNr16S16S

MajoritateamoleculelorARNmsuntmonocistronice(conMajoritateamoleculelorARNmsuntmonocistronice(conininformaininformaiedelaosingurgeniedelaosingurgen))

LamoleculeleARNmdelaEKnuexistsecvenLamoleculeleARNmdelaEKnuexistsecvenSDSD,,

ribozomulseataribozomulseataeazlacapulMeteazlacapulMetGG55

PK PK

EK EK

DeDeiprocesuldetraducereainformaiprocesuldetraducereainformaieigeneticeestesimilarlaPKieigeneticeestesimilarlaPKiEK,iEK,existdiferenexistdifereneenstructuramoleculelordeARNmnstructuramoleculelordeARNm

PentrufiecaresecvenPentrufiecaresecvencodificatoarecodificatoare(ge(genn),ARNmdelaPKcon),ARNmdelaPKconinecteosecveninecteosecvenRBSRBS,lacarese,lacarese

ataataeazcteunribozomeazcteunribozom,fiecaresecven,fiecaresecvencodificatoarefiindtradusseparatcodificatoarefiindtradusseparat..

5 3

CapMetG 5

UTR 3

UTRSecvencodificatoareStart StopCoadpoliA

Structura tipic a unui ARNm uman(UTR=UntranslatedRegion=regiunenetradus)

CodulgeneticCodulgenetic

LegturalogicLegturalogicntresecvenntresecvenadenucleotidedinARNmadenucleotidedinARNmisecvenisecvenadeaminoacizidinproteineadeaminoacizidinproteine

Codon=setde3nucleotidedinARNmcesunttraduseCodon=setde3nucleotidedinARNmcesunttradusentrntrunAAunAA

CaracteristicilecoduluigeneticCaracteristicilecoduluigenetic

3.Codulgeneticnuaresemnedepunctua3.Codulgeneticnuaresemnedepunctuaieie

InformaInformaiadinARNm(secveniadinARNm(secvenadenucleotide)adenucleotide)estecititcontinuuestecititcontinuuNuexistnucleotidecaressemnificepazNuexistnucleotidecaressemnificepaz,p,punct,virunct,virguletcguletc

4.Codulgeneticesteuniversal4.Codulgeneticesteuniversal

AcelaAcelaicodoncodificunacelaicodoncodificunacelaiAAlatoateorganismeleiAAlatoateorganismele

ExcepExcepii:ii:

5.Codulgeneticestedegenerat5.Codulgeneticestedegenerat

MaimulMaimulicodonipotcodificaacelaicodonipotcodificaacelaiAAiAA

1.Codoniisuntciti1.Codoniisuntcitiiindirecndirecie5ie5 33

2.Codulgeneticestenesuprapus2.Codulgeneticestenesuprapus

CodoniidinARNmsuntcitiCodoniidinARNmsuntcitiilasuccesiv,nuaunucleotidecomuneilasuccesiv,nuaunucleotidecomune

AUG=celmaifrecventcodonSTART=Met(EK)/fMet(PK)AUG=celmaifrecventcodonSTART=Met(EK)/fMet(PK)

CodoniSTART/STOPCodoniSTART/STOP

LaanumiteorganismeGUG/UUG=STARTLaanumiteorganismeGUG/UUG=START

UAG,UGA,UAA=codoniSTOPUAG,UGA,UAA=codoniSTOP

(codoninonsens)(codoninonsens)

nmitocondrii(UGA=Trp),nmitocondrii(UGA=Trp),nanumitemicroorganismePK,EKnanumitemicroorganismePK,EK

ARNtARNt

Moleculemici:70Moleculemici:70100b100b

Au22nAu22nnanumitepozinanumitepoziii(poziii(poziiifixe),iifixe),cenuvariazlamajoritateaARNtcunoscutecenuvariazlamajoritateaARNtcunoscute

ConConineoseriedebazemodificate:dihidroineoseriedebazemodificate:dihidrouridina(DHU)uridina(DHU)ribosilribosiltimina(rT)=timina(rT)=55metilmetiluridinuridin(Umetilat)(Umetilat)pseudopseudouridina(uridina())inosina(I)inosina(I)

=Gdezaminata=Gdezaminata

=moleculeadaptor=moleculeadaptorntrecodonintrecodoniiAAiAA

ToatemoleculeleARNtaulacapul3ToatemoleculeleARNtaulacapul3

secvensecvenadenucleotideCCA=adenucleotideCCA= Capulacceptor(capulCCA)Capulacceptor(capulCCA)

amoleculelordeARNt=amoleculelordeARNt=StructurasecundarStructurasecundar FrunzdetrifoiFrunzdetrifoi

3buclem.c.:3buclem.c.: buclaDbuclaD

are2DHUare2DHUnpozinpoziiifixeiifixe

buclabucla

are1are1

npozinpoziiefixiefix

buclaanticodonuluibuclaanticodonului

nucleotideledinpozinucleotideledinpoziiile34,35,36=iile34,35,36= AnticodonAnticodon

4regiunid.c.=bra4regiunid.c.=braee

1b1buclvariabiluclvariabil,adi,adiionalional,d,dedimensiunemicedimensiunemic

amoleculelordeARNt=amoleculelordeARNt=iariarStructuraterStructurater LiteraLLiteraLntoarsntoars

FiecaremoleculARNtataFiecaremoleculARNtataeazcovalentlacapulCCAeazcovalentlacapulCCA33

unAAunAA

ReacReaciadeiadencrcareaunuiAAlaomoleculdeARNtncrcareaunuiAAlaomoleculdeARNt=aminoacilare=aminoacilare aminoacilaminoacilARNtARNtsintetaze(AAS)sintetaze(AAS)

1.1. AA+ATPAA+ATP AminoacilAminoacilAMP+PPiAMP+PPi

2.2. AminoacilAminoacilAMP+ARNtAMP+ARNt AminoacilAminoacilARNt+AMPARNt+AMP

FuncFuncionareamoleculelorARNtcaadaptorionareamoleculelorARNtcaadaptorntrercodonintrercodoniiAA,iAA,sebazeazsebazeaznprimulrndpefaptulcfiecarenprimulrndpefaptulcfiecare

speciemoleculardeARNtataspeciemoleculardeARNtataeazunanumitAAeazunanumitAA

ExistcteExistcte1s1speciemoleculardeAASpeciemoleculardeAAS((i,i,deregulderegul,numaiuna)ptrfiecareAA,numaiuna)ptrfiecareAAFiecarespeciemoleculardeAASareoasemeneaconformaFiecarespeciemoleculardeAASareoasemeneaconformaiemoleculariemolecular,,nctpoatelegaunsingurtipdeAAnctpoatelegaunsingurtipdeAA

doarcuanumitetipurideARNtdoarcuanumitetipurideARNt

FidelitateatraduceriiinformaFidelitateatraduceriiinformaieigeneticesebazeazpeieigeneticesebazeazpe::

aminoacilareacorectaunuiARNtaminoacilareacorectaunuiARNt

mperechereacorectcodonmperechereacorectcodon

anticodonanticodon

EtapeletraduceriigeneticeEtapeletraduceriigenetice

IniIniiereaierea

AtaAtaareasubunitareasubunitiiribozomalemici(30S)lasecveniiribozomalemici(30S)lasecvenaSDdinARNmaSDdinARNm

CodonulAUGesteadusCodonulAUGesteadusnsitusulPalsubunitnsitusulPalsubunitiirbzmiciiirbzmici

iereiereFactori(proteine)deiniFactori(proteine)deini

IF1,IF2,IF3IF1,IF2,IF3

SeataSeataeazfMeteazfMetARNtARNtMetMetisecodonulAUGdinARNmcuanticodonulCAUdinARNtisecodonulAUGdinARNmcuanticodonulCAUdinARNtMetMet

SeataSeataeazsubunitatearbzmareeazsubunitatearbzmare(50S)(50S)

Acesteetapesuntcoordonatede3factorideiniAcesteetapesuntcoordonatede3factorideiniiereiere

IF1,IF2,IF3IF1,IF2,IF3

DupataDupataareasubunitareasubunitii50S,cei3IFsedesprindii50S,cei3IFsedesprind

SintezalanSintezalanuluipeptidiculuipeptidicncepedelacapulNHncepedelacapulNH

22

ElongareaElongarea

TraducereainformaTraducereainformaieidepeARNmsefaceieidepeARNmsefacendirecndirecia5ia5 33

AdiAdiiafiecruiAAserealizeazprinreaciafiecruiAAserealizeazprinreaciicomplexeceserepetptrfiecareAAiicomplexeceserepetptrfiecareAA

AA2AA2ARNtARNt situsulAsitusulA

SeSemperecheazcodonuldinARNmcuanticodonuldinARNtmperecheazcodonuldinARNmcuanticodonuldinARNt

AtacnucleofilicalNH2dinAA2asupraCOOHdinfMetAtacnucleofilicalNH2dinAA2asupraCOOHdinfMet FormareaprimeilegturipeptidiceFormareaprimeilegturipeptidice

(peptidil(peptidiltransferazprezenttransferazprezentn50S)n50S)

RezultunpeptidilRezultunpeptidilARNt:aMetARNt:aMetAA2AA2ARNtARNt

peptidilpeptidilARNtsaredinsitusulAARNtsaredinsitusulAnsitusulPnsitusulP SitusulAesteacumliberpentruataSitusulAesteacumliberpentruataareaunuiAA3areaunuiAA3ARNtARNt

RbzsedeplaseazpemoleculaARNmcuuncodonRbzsedeplaseazpemoleculaARNmcuuncodon

Factori(proteine)deelongareFactori(proteine)deelongare

EFEFTs,EFTs,EFTu,EFTu,EFGG

TerminareaTerminarea

CodoniiSTOP:UAG,UGA,UAACodoniiSTOP:UAG,UGA,UAA

DupataDupataareaultimuluiAA,peptidilareaultimuluiAA,peptidilARNtesteinsitusulAalrbzARNtesteinsitusulAalrbzFactori(proteine)determinareFactori(proteine)determinare

RF1,RF2,RF3RF1,RF2,RF3

peptidilpeptidilARNtestetranslocatdinsitusulAARNtestetranslocatdinsitusulAnsitusulPnsitusulP

LegturadintrepeptidilLegturadintrepeptidiliARNtestehidrolizatiARNtestehidrolizat

SunteliberaSunteliberai:i: CatenapeptidicCatenapeptidic

UltimulARNtUltimulARNt

RibozomulsedisociazdeARNmRibozomulsedisociazdeARNm,apoi70S,apoi70S 50S+30S50S+30S

ProteinelesuntsintetizatenumaindirecieNCRibozomiisedeplaseazpeARNmncepndcucapul5alacestuia

Fiecareribozomsintetizeazunsingurpolipeptid(pemoleculeleARNmpolicistronicseataeazmaimuliribozomi)

Alfabet grecesc Alfabet grecesc

Se citeteLiter micLiter mareSe citeteLiter micLiter mare

niualfaksibetaomicrongamapideltarho (ro)epsilonsigmazetatauetaipsilon thetaphi (fi)iotachi (hi)kappapsilambdaomegamiu

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