《分子生物学》课程教学课件（PPT讲稿）Chaptor 6 The biosynthesis of protein（translation）

1-2 Prokaryotic mRNAs have a ribosome binding site (RBS)that recruits the translational machinery; Ribosome binding site(RBS,核糖体结合位点) orSD-sequence(SD序列)in prokaryotic mRNA, complementary with the sequence at the 3'end of 16S rRNA; 3UUCCUCCACUAG5 16S rRNA 5NNNNGGAGGNNNNNNNAUGNN3 stop RBS start stop RBS start RBS start stop 5PPP 5-9bases 000000000000000 G00000000000000 000000000000000 structure of prokaryotic mRNA 16

16 Ribosome binding site (RBS，核糖体结合位点) or SD-sequence（SD序列） in prokaryotic mRNA, complementary with the sequence at the 3’ end of 16S rRNA; structure of prokaryotic mRNA 1-2 Prokaryotic mRNAs have a ribosome binding site (RBS) that recruits the translational machinery;

Initiation codon araB -UUUGGAUGGAGUGAAACGAUGGCGAUU- galE -AGCCUAAUGGAGCGAAUUAUGAGAGUU- lacl -CAAUUCAGGGUGGUGAUUGUGAAACCA- lacZ -UUCACACAGGAAACAGCUAUGACCAUG- Q B phage replicase -UAACUAAGGAUGAAAUGCAUGUCUAAG- X174 phage A protein -AAUCUUGGAGGCUUUUUUAUGGUUCGU- R17 phage coat protein -UCAACCGGGGUUUGAAGCAUGGCUUCU- Ribosomal S12 -AAAACCAGGAGCUAUUUAAUGGCAACA- Ribosomal L10 -CUACCAGGAGCAAAGCUAAUGGCUUUA- trpE -CAAAAUUAGAGAAUAACAAUGCAAACA- trp leader -GUAAAAAGGGUAUCGACAAUGAAAGCA- 3'end of 16S rRNA 3 HOAUUCCUCCACUAG-5 Figure 26-26.Some translation initiation sequences recognized by E.col/ribosomes. [After Steitz,J.A.,in Chambliss,G.,Craven,G.R.,Davies,J.,Davis,K.Kahan,L.and Nomura,M (Eds.),Ribosomes.Structure,Function and Genetics,pp.481-482,University Park Press (1979).] Copyright 1999 John Wiley and Sons.Inc.All rights reserved

30H G 3'end of A 16S rRNA A U c UCCUCCA 5 3 GAUUCCUAGGAGGUUUGACCUAUGCGAGCUUUUAGU-Messenger RNA fMet-Arg-Ala-Phe'Ser-Polypeptide The ribosome binding site is frequently called the Shine-Dalgarno sequence;

The ribosome binding site is frequently called the Shine-Dalgarno sequence;

SD sequence(SD序列) 原核生物mRNA起始密码子上游大约10nt处，有一个富含 嘌呤序列； 其全部或部分按顺序为：AGGAGGU: 与核糖体16 S rRNA3-端富含嘧啶的序列互补； 促使核糖体与mRNA结合，启动蛋白质合成； 它被称为Shine-.Dalgarno sequence或SD序列，以纪念其 发现者：

SD sequence（SD序列） 原核生物mRNA起始密码子上游大约10nt处，有一个富含 嘌呤序列； 其全部或部分按顺序为： AGGAGGU； 与核糖体16S rRNA 3‘ –端富含嘧啶的序列互补； 促使核糖体与mRNA结合，启动蛋白质合成； 它被称为Shine-Dalgarno sequence或SD序列，以纪念其 发现者；

1-3 Eukaryotic mRNA are modified at their 5'and 3'ends to facilitate translation; 真核mRNA的5'和3端被修饰，以便于翻译； 5'NN NNNAUGGNN3'←一Kozak sequence start stop AUG ■AAAAA3 5'cap aoo00o00000000o 真核mRNA采用甲基化的帽子结构来结合核糖体； 一旦结合，核糖体以5’3的方向扫描mRNA,寻找 AUG起始密码子； Kozak sequence（Kozak序列)：提高翻译效率； Poly-A at the3'end:促进核糖体循环利用的效率；

Kozak sequence • 真核mRNA采用甲基化的帽子结构来结合核糖体； 一旦结合，核糖体以5’→3’的方向扫描mRNA，寻找 AUG起始密码子； • Kozak sequence（Kozak序列）：提高翻译效率； • Poly-A at the 3’ end ：促进核糖体循环利用的效率； 1-3 Eukaryotic mRNA are modified at their 5’ and 3’ ends to facilitate translation； 真核mRNA的5’和3’端被修饰，以便于翻译;