清华大学：《分子生物学》课程PPT教学课件（基因ene）第十六章 逆转录病毒和逆转座子（Retroviruses and retroposons）

Chapter 16 Retroviruses And retroposons 清革大当

Chapter 16 Retroviruses And retroposons

16.1 Introduction 16.2 The retrovirus life cycle involves transposition-like events 16.3 Retroviral genes codes for polyproteins 16.4 Viral DNA is generated by reverse transcription 16.5 Viral DNA integrates into the chromosome 16.6 Retroviruses may transduce cellular sequences 16.7 Yeast Ty elements resemble retroviruses 16.8 Many transposable elements reside in D.melanogaster 16.9 Retroposons fall into two classes 16.10 The Alu family has many widely dispersed members 清莘大当

16.1 Introduction 16.2 The retrovirus life cycle involves transposition-like events 16.3 Retroviral genes codes for polyproteins 16.4 Viral DNA is generated by reverse transcription 16.5 Viral DNA integrates into the chromosome 16.6 Retroviruses may transduce cellular sequences 16.7 Yeast Ty elements resemble retroviruses 16.8 Many transposable elements reside in D. melanogaster 16.9 Retroposons fall into two classes 16.10 The Alu family has many widely dispersed members

16.1 Introduction Retroposon is a transposon that mobilizes via an RNA form;the DNA element is transcribed into RNA,and then reverse- transcribed into DNA,which is inserted at a new site in the genome. 清苇大当

Retroposon is a transposon that mobilizes via an RNA form; the DNA element is transcribed into RNA, and then reverse￾transcribed into DNA, which is inserted at a new site in the genome. 16.1 Introduction

9.1 Introduction RNA Figure 16.1 The reproductive cycles of retroviruses and retroposons involve alternation of reverse transcription from RNA to DNA with transcription from DNA to RNA.Only INTRACELLULAR retroviruses can generate infectious particles. EXTRACELLULAR Retroposons are confined to an intracellular cycle. Retrovirus 情華大当

Figure 16.1 The reproductive cycles of retroviruses and retroposons involve alternation of reverse transcription from RNA to DNA with transcription from DNA to RNA. Only retroviruses can generate infectious particles. Retroposons are confined to an intracellular cycle. 9.1 Introduction

16.2 The retrovirus life cycle involves transposition like events LTR is an abbreviation for long-terminal repeat. 清苇大当

LTR is an abbreviation for long-terminal repeat. 16.2 The retrovirus life cycle involves transposition like events

16.2 The retrovirus RNA life cycle involves Reverse transcription transposition like LTR LTR Linear DNA NM八八八八八入MNNN events Figure 16.2 The retroviral Integration Circul arization ceaetwTgae RNA genome into duplex DNA,which is inserted Provirus N八八N八NMN入N into the host genome,in Transcrption order to be transcribed into RNA. RNA 情華大当

Figure 16.2 The retroviral life cycle proceeds by reverse transcribing the RNA genome into duplex DNA, which is inserted into the host genome, in order to be transcribed into RNA. 16.2 The retrovirus life cycle involves transposition like events

16.2 The retrovirus life cycle involves transposition like events 10-80 80-100 170-1260 env -2000 ~2900 w1800 月 g wn odaguo 湖 8co Processing日 prcr w Each gene generates several protein produds n Gag。 w mponent c Pol e IN=integrase (integrates provirus DNA into genome) Figure 16.3 The genes of the retrovirus are expressed as polyproteins that are processed into individual products. 清苇大兰

Figure 16.3 The genes of the retrovirus are expressed as polyproteins that are processed into individual products. 16.2 The retrovirus life cycle involves transposition like events

16.2 The retrovirus life cycle involves transposition like events Budding initiates 3 Virus released Figure 16.4 Retroviruses (HIV) bud from the plasma 0.1um membrane of an Bud elongates Virus matures infected cell. Photograph kindly provided by Matthew Gonda. 情莘大兰

Figure 16.4 Retroviruses (HIV) bud from the plasma membrane of an infected cell. Photograph kindly provided by Matthew Gonda. 16.2 The retrovirus life cycle involves transposition like events

16.2 The retrovirus life cycle involves transposition like events RNA form ofvirus Figure 16.5 0-80RU5 gag por env U310-80 Retroviral RNA ~2000 ~2900 ~1800 80-10心 70-1263 ends in direct Linear DNA form of virus repeats (R),the U3 RU5 gag por env U3 RU free linear DNA ends in LTRs, LTR LTR 250-1400bp and the provirus Integrated DNA form of virus ends in LTRs U3 has lost 2 bp U5 has lost 2 bp that are shortened by Host U3 RU5 gag pol env Host two bases each. 4-6 bp repeat of 4-6 bp repeat of target DNA target DNA 清苇大兰

Figure 16.5 Retroviral RNA ends in direct repeats (R), the free linear DNA ends in LTRs, and the provirus ends in LTRs that are shortened by two bases each. 16.2 The retrovirus life cycle involves transposition like events

Retrovirus provides plus strand RNA R U5 U3 R Prmer t恨NA anneals to binding site on retroviraRN 16.2 The retrovirus 55 sR.3 Reverse transcriptase life cycle involves starts synthesis of minus strand DNA 3 transposition like events Enzymes reaches end of template strand,generating strong stop minus DNA Strong stop minus Figure 16.6 Minus strand 5'terminal region of RNA strand is degraded DNA is generated by switching templates during New end◆ Single-stranded DNA R region pairs with reverse transcription 3teminus in first jump to anothey Pairing retroviral RNA 5'nu Reverse transcriptase 清菜大当 3

Figure 16.6 Minus strand DNA is generated by switching templates during reverse transcription. 16.2 The retrovirus life cycle involves transposition like events