23 mar 2014 TRANSCRIEREA genetică PK TRANSCRIEREA genetică PK + EK + EK TRADUCEREA informa TRADUCEREA informa ț ț iei genetice iei genetice CODUL GENETIC CODUL GENETIC Secția Biochimie anul II
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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