第二讲真核生物的RNA转录1课件.ppt

1、真核生物中与转录相关的顺式元件（真核生物中与转录相关的顺式元件（ciscis-factorsfactors）真核生物转录的起始；真核生物转录的起始；4、真核生物转录的延伸；、真核生物转录的延伸；一、一、真核生物与转录相关的顺式元件真核生物与转录相关的顺式元件（ciscis-factors-factors）l l l Cap site;initiation point(+1)Capping m7GpppA/G-70-AUG-(in mRNA)Initiation region 1-4Kb -110 -70 -30 +1 GC island CAAC/T box TATA box Cap Enha

2、ncer UPE core promoter Promoter(basic factor)Promoter for basic transcription l TATA box/Hogness box/Goldberg-Hogness box(-30)Rich AT and rich GC-T A T A A (T)A A (T)-rich GC 82 97 93 85 63(37)83 50(37)1-4Kb -110 -70 -30 +1 GC island CAAC/T box TATA box Cap Enhancer UPE core promoter Promoter(basic

3、factor)Promoter for basic transcription l l CAAT box(CAT box UPE)and GC island GGGCGGG(T)-CAATCT-Range 30 bp 1-4Kb -110 -80 -70 -30 +1 GC island CAATCT box TATA box Cap Enhancer UPE core promoter Promoter(basic factor)应答元件与转录调控因子的对应关系应答元件与转录调控因子的对应关系GRE:糖皮质激素应答元件糖皮质激素应答元件;TRE:佛波酯应答元件佛波酯应答元件;SRE:血清应血

4、清应答元件；答元件；人金属硫蛋白编码基因上游的复合应答元件结构人金属硫蛋白编码基因上游的复合应答元件结构 Enhance expression Basic expressionPosition not be fixed isolated region Bi-directional element Mono-directional element Enhancer PromoterNo for special gene only for special gene（1）、）、Enhancer与与Promoter的比较的比较 SV40 早期基因转录单位早期基因转录单位 S-200 S 72bp 72

5、bp 72bp region deletion S transcription go down into upstream of-globin gene Transcription up 200X Cell&tissue specialty of Enhancer effect Distance effect(over 2 kb)Orientation（）-无方向性无方向性 Enhancer 的结构的结构-Enhancer 由由的的(Enhancer Element)组成组成-每个每个Enhancer Element 必需由两个必需由两个紧密相连紧密相连的的(Enhanson）组成组成-各个各

6、个Enhanson(cis-factor)与与(trans-factor)结合结合 增强特异性转录增强特异性转录 促进转录的复合体促进转录的复合体 +UPE+core promoter基本转录复合体基本转录复合体Enhancer.Specifical transc.Factor(tran-factor)Specifical transc.Factor(tran-factor)+Activation（激活）激活）domain Of Enhancer complex Activation（激活）激活）domain of Enhancer complex.Enhancer ElementEnhanc

7、er Element(20TFIIs TIC 转录启动转录启动 (Transcriptional Initiation Complex)needed for RNApol I,II,III；Very high conserved C-end domain of 180 aa；Binds with DNA in（小沟）小沟）&；：A sort of protein complex(&8)Transcriptional；TATA +1 circle minor groove（环绕环绕DNA小沟）小沟）TFII A TBP of TFII D pre-TIC TFIIA：Binds to TFII

8、D Enhances TFII D binding to TATA box Stabilizing the DNA-TFII D complex TFIIB：TFIIB binds to TBP of TFIID and RNA pol.II TFIIB as a allowing recruitment（招募）招募）of RNApol II to TIC；TFIIF：Including two subunits of,Binding and recruiting（招募）（招募）RNApol II to assemble TIC TFII F RNApol IITFII B Basic TIC

9、 TFIIH;Helicase activity(ATPase)&kinase activity Phosphorylation of CTD of RNApol IIO DNA repair TFIIE;Associate with TFIIH kinase complete TIC EH真核真核RNA聚合聚合酶对酶对DNA模板模板的识别的识别TFIIE，HmRNA Promoter clearance Transcription startingFE H B D ARNApol I;Located in nucleolus For pre-rRNA(18s 5.8s 28s )80-85%

10、of total RNATwo control domains included in cis-factorTrans-factor including Including 4 subunits 1 of TBP(TATA biding protein)3 of TAF(TBP associate factor)UBF(UPE Binding Factor)SL(Selectivity factor)UPE(upstream promoter element)Core promoter UBF+UPE UBF+Part of core promoter Two UBF interaction

11、causing DNA to form a loop3 TAF1 TBPSL UPE core promoter UBF UBF v RNApol I起始复合物的组装过程：起始复合物的组装过程：Pre-rRNA Allows RNApol binding complex to initiate RNApol RNApol III：Located in 16 or more subunits For 5s pre-rRNA；4s pre-tRNA；U6 snRNA(small nuclear RNA)；Cytosolic RNA；-cis-factor includingtwo highly c

12、onserved regions lie +1 -A box;TGGCNNAGTGG(D-loop of tRNA)-B box;GGTTCGANNCC (TC-loop of tRNA)：Tans-factor binding to A,B box TFIII C+1 A box B box tDNA v TFIIIB allows RNApol III to bindand initiate transcription tRNA RNApol III+1v-cis-factor including：A box;+50 to+65 bpC box;located 81-99bp downst

13、ream from+1-Trans-factor TFIII A：specific C box binding protein&allows 指导指导 TFIIIC结合到启动子结合到启动子A区上区上 TFIII C：与与A区结合，指导区结合，指导TFIIIB结合到启动子上游；结合到启动子上游；RNApol III for 5s pre-rRNA RNApol IIITFIIIC TFIIIA +1 A box C box TFIIIB 5S rRNA 5s pre-rRNA transcription DNA-binding domainactivation domainl Cys/Cys,C

14、ys/His (Zinc finger)l HelixloopHelix (HLH or bHLH)l Leu zipper (bZIP)1、DNA结合结构域种类及结构特点：结合结构域种类及结构特点：23 aa/copy one finger9 direct repeats,23aa/copy2Cys/2His or 2Cys/2Cys types2Cys(2C)Zn 2His(2H)to form finger of 1-helix&1-sheetPeptide chainLec zipperdimerization螺旋环螺旋（螺旋环螺旋（helix-loop-helix）2、Transcr

15、iption activation domain (most TF have one or more than one of these domain)Group 1 Yeast GAL4 typifies（代表）代表）this group,49 aa domain with 11 acidic aa Group 2 Sp1（可与可与GC盒结合的激活因子）盒结合的激活因子）have two this domain,one of these,39 Gln in a span of 143 aaGroup 3 CTF has a domain of 84 aa,19 of which are Pr

16、oAfter 100 Ntl promoter clearance elongation complex l RNApol II+（helicase）Transcription 55kd TFII J stimulation elongation1、从起始复合体到延伸复合体：、从起始复合体到延伸复合体：五、五、Transcription Elongation六、真核生物转录的终止六、真核生物转录的终止l RNApol II leave from terminator l RNA released from Triplex(RNA,DNA,RNApol II)Difficult to identify the primary transcript In Eukaryotes because pre-mRNA processing 真核基因转录的真核基因转录的终止终止