《分子生物学》课程PPT教学课件（讲义）lect7 Translation

Translation

Translation

Composition of ribosomes 2 subunits, each composed of about 60% RNA and about 40% protein(by mass) Small ribosomal subunit 1 rRNA(bacteria), 18S rRNA(eukaryotes) 21(bacteria) to 33(eukaryote) proteins Initial binding of mRNA and initiator met-tRNA Large ribosomal subunit 23s 5s rRNA(bacteria), 28S, 5.8S,& 5srrNA (eukaryotes 31(bacteria) to 49(eukaryote) proteins Forms complete, catalytic ribosome

Composition of ribosomes • 2 subunits, each composed of about 60% RNA and about 40% protein (by mass). • Small ribosomal subunit – 16S rRNA (bacteria), 18S rRNA (eukaryotes) – 21 (bacteria) to 33 (eukaryote) proteins – Initial binding of mRNA and initiator met-tRNA • Large ribosomal subunit – 23S & 5S rRNA (bacteria), 28S, 5.8S, & 5S rRNA (eukaryotes) – 31 (bacteria) to 49 (eukaryote) proteins – Forms complete, catalytic ribosome

Ribosomes核糖体 原核和真核生物核糖体的组成及功能 核糖体亚基 TRNAs蛋白 RNA的特异顺序和功能 细菌 70S50s23s-2904b31种(L1-31)含 CGAAC和 GTyCG互补 2.5×106D 5S=120b 66RNA 30S 16$=1542b 21F+(S1-S21)16SRNA(CCUCCU)FHS-D 顺序( AGGAGG)互补 哺乳动物 80S60S28S-4718b49种有GAUC和RNAM的TvCG互补 4.2×106D 5S=120b 60%RNA 5.8S=160b 40S18S=1874b33种 和Capm7G结合

Ribosomes核糖体 原核和真核生物核糖体的组成及功能 核糖体亚基 rRNAs 蛋白 RNA的特异顺序和功能 细菌 70S 50S 23S=2904b 31种(L1-L31）含CGAAC和GTψCG互补 2.5×106D 5S=120b 66%RNA 30S 16S=1542b 21种(S1-S21) 16SRNA(CCUCCU)和S-D 顺序(AGGAGG)互补 哺乳动物 80S 60S 28S=4718b 49种 有GAUC和tRNAfMat的TψCG互补 4.2×106D 5S=120b 60%RNA 5.8S=160b 40S 18S=1874b 33种 和Capm7G结合

核糖体的作用位点 (1)A位点(或称 acceptor site)可以进入 氨基酰RNA( aminoacyl-RNA) (2)P位点(或称供位, donor site)是被肽基 酰+RNA( peptidyl-tRNA)所占据。 (3位点 Exit site)脱性tRNA( deacylated tRNA)短暂地占据

核糖体的作用位点 • ⑴A位点（或称 acceptor site）可以进入 氨基酰-tRNA(aminoacyl-tRNA)。 • ⑵ P位点(或称供位，donor site) 是被肽基 酰-tRNA(peptidyl-tRNA)所占据。 • (3)E位点(Exit site) 脱酰tRNA(deacylated￾tRNA)短暂地占据

3 sites on ribosome for interaction with tRNAs E A CH3 CH2 NH+CH-C÷NH亠cH-CAcc5 NH,CH-C=ACC Exit site for alanylcysteiny l-tRNA ethionyl-tRNA m free tRNA ACA 5 AC 5 peptidyl-tRNA aminoacyl-tRNA

3 sites on ribosome for interaction with tRNAs E P A 5' UAC 5' 2 methionyl-tRNA met 2 3 ACC O C 2 CH CH NH CH S CH m 5' SH 2 2 ACA 5' ACC O CH C CH NH 3 O CH C CH NH alanylcysteinyl-tRNA cys peptidyl-tRNA aminoacyl-tRNA Exit site for free tRNA

Large ribosomal subunit, 9A resolution 5S rRNA region L7几12 Ban,. Moore, steitz Cell.Vol.93.1105-1115 1998 Ittp://www.life.nthu edu. tw /-b830356/ribosome 100A e. html 55 TRNA region 5s rRNA regi L712 L7几L1

Large ribosomal subunit, 9 A resolution http://www.life.nthu .edu.tw /~b830356/ribosom e.html Ban, ..Moore, Steitz, Cell, Vol. 93, 1105-1115, 1998

30s ribs subunit from side that contacts the 50s subunit http://chem-faculty.ucsdedu/joseph/ 50S ribs subunit from side that Ribosome_ Structure_ Gallery. html Schluenzenet al. Cell (2000)102, 615-623 contacts the 30s subunit Ban,. P. Moore, T Steitz; Science(2000)289 905-920

3-D views of ribosome subunits http://chem-faculty.ucsd.edu/joseph/ Ribosome_Structure_Gallery.html Schluenzen et al. Cell (2000) 102, 615-623 Ban, ...P. Moore, T. Steitz; Science (2000) 289 905-920 30S ribs subunit, from side that contacts the 50S subunit 50S ribs subunit, from side that contacts the 30S subunit

核糖体结合位点 SD sequence Ribosome binding site(rbs) ·在原核生物mRNA起始密码子上游8-13个核苷酸 处,通常有5- AGGAGGU-3的富含嘌呤的保守序 列,这段序列可与核糖体16 SrrNA的3端序列5 ACCUCCU-3进行碱基配对,因此成为核糖体结 合位点 Shine-Dalgarno序列或SD序列 ·SD序列的作用是相对于起始密码子而正确定位核 糖体 G GUAUG mRNA 3 AUCCUCCA 16S rrNA

核糖体结合位点 SD sequence Ribosome binding site (RBS) • 在原核生物mRNA起始密码子上游8-13个核苷酸 处，通常有5’-AGGAGGU-3’的富含嘌呤的保守序 列，这段序列可与核糖体16S rRNA的3’端序列5’- ACCUCCU-3’ 进行碱基配对，因此成为核糖体结 合位点Shine-Dalgarno序列或SD序列 • SD序列的作用是相对于起始密码子而正确定位核 糖体 GUAGGAGGUGUAUG mRNA 3’ 16S rRNA AUCCUCCA

Function: For the position of ribosome correctly with respect to the initiation codon E coli trp A 5)AGC CGAGGGGAAAUCUGAU GGAACGCUA C(3) E coli araB U UUGGA UGGAGUGAAACGAUGGCGAUUGCA E coli lacI CAA UUCAGGGUGGUGAAUGUGAAACCAGUA oX174 phage A protein AA UCUUGGAGGCUUUUUUAUGGUUCGUUCU a phage cro AU GUACUAAGGAGGUUGUAUGGAACAACGC Shine- Dalgarno sequence; Initiation codon pairs with 16srRNA pairs with fMet-tRNAIMet G 3’ End of Prokaryotic mrNA 16S rRNA with consensus UCCUCCA Shine-Dalgarno (5)GA UUCCUAGGAGGUUUGACCUAUGCGAGCUU U UA G U(3) sequence (b)

AUG Function: For the position of ribosome correctly with respect to the initiation codon

Translation in procaryotes 原核生物的翻译可以分为三个阶段 initiation起始 elongation延长 termination终止 每一步都需要一些特定的蛋白质分子参与和 trNas,mRNA,and/ or ribosomes的相互作用

原核生物的翻译可以分为三个阶段 • initiation起始 • elongation延长 • termination终止 每一步都需要一些特定的蛋白质分子参与和 tRNAs, mRNA, and/or ribosomes的相互作用 Translation in procaryotes