清华大学：《分子生物学》（英文版）Chapter 14 Recombination and repair

Chapter 14 Recombination and repair 莘大

Chapter 14 Recombination and repair

14.1 Introduction 14.2 Breakage and reunion involves heteroduplex dnA 14.3 Double-strand breaks initiate recombination 14.4 Double-strand breaks initiate snapsis 14.5 Bacterial recombination involves single-strand assimilation 14.6 Gene conversion accounts for interallelic recombination 14.7 Topological manipulation of dna 4.8 Specialized recombination involves breakage and reunion at specific sites 14.9 Repair systems correct damage to DNA 14.10 Excision repair systems in E coli 14.11 Controlling the direction of mismatch repair 14.12 Retrieval systems in E coli 14.13 Reca triggers the sos system 14.14 Eukaryotic repair systems 消当

14.1 Introduction 14.2 Breakage and reunion involves heteroduplex DNA 14.3 Double-strand breaks initiate recombination 14.4 Double-strand breaks initiate snapsis 14.5 Bacterial recombination involves single-strand assimilation 14.6 Gene conversion accounts for interallelic recombination 14.7 Topological manipulation of DNA 14.8 Specialized recombination involves breakage and reunion at specific sites 14.9 Repair systems correct damage to DNA 14.10 Excision repair systems in E. coli 14.11 Controlling the direction of mismatch repair 14.12 Retrieval systems in E. coli 14.13 RecA triggers the SOS system 14.14 Eukaryotic repair systems

14.1Introduction Bivalent is the structure containing all four chromatids(two representing each homologue )at the start of meiosis Breakage and reunion describes the mode of genetic recombination, in which two dna duplex molecules are broken at corresponding points and then rejoined crosswise(involving formation of a length of heteroduplex dNa around the site of joining) Site-specific recombination occurs between two specific(not necessarily homologous)sequences, as in phage integration/excision or resolutionof cointegrate structures during transposition Synapsis describes the association of the two pairs of sister chromatids representing homologous chromosomes that occurs at the start of meiosis resulting structure is called a bivalent Synaptonemal complex describes the morphological structure of synapsed chromosomes Transposition refers to the movement of a transposon to a new site in the genome 消当

Bivalent is the structure containing all four chromatids (two representing each homologue) at the start of meiosis. Breakage and reunion describes the mode of genetic recombination, in which two DNA duplex molecules are broken at corresponding points and then rejoined crosswise (involving formation of a length of heteroduplex DNA around the site of joining). Site-specific recombination occurs between two specific (not necessarily homologous) sequences, as in phage integration/excision or resolution of cointegrate structures during transposition. Synapsis describes the association of the two pairs of sister chromatids representing homologous chromosomes that occurs at the start of meiosis; resulting structure is called a bivalent. Synaptonemal complex describes the morphological structure of synapsed chromosomes. Transposition refers to the movement of a transposon to a new site in the genome. 14.1 Introduction

P rogress through m eiosis 14.1 M ole cular interactions M Each chrom osome has chrom somes Introduction AN replicated, and consists of become visible, often 2 sister chromatid s attached to nuclear envelope A MVV Figure 14.1 Recombination Zygotene A Initiation Chromosom es begin occurs during the first meiotic reglon or regions AAAAA prophase. The stages of N prophase are defined by the P achytene appearance of the Synaptonem al complex extends chromosomes each of which along entire length of bosom es consists of two replicas(sister ) /VA Strand exchange NUM VA Single strands exchange chromatids), although the Diplotene duplicated state becomes Chromosomes A人A in of exchange separate but are held visible only at the end. The together by hastata N molecular interactions of any individual crossing-over event Diakinesis involve two of the four duplex Chromosom es A Resolution condense, detach from envelope DNAS chiasmata remain. a 八 4 chromatids becom 请莘大

Figure 14.1 Recombination occurs during the first meiotic prophase. The stages of prophase are defined by the appearance of the chromosomes, each of which consists of two replicas (sister chromatids), although the duplicated state becomes visible only at the end. The molecular interactions of any individual crossing-over event involve two of the four duplex DNAs. 14.1 Introduction

A antigen gaNAdo. 1 14.1 alp1-R Fuon 1 Introduction A transfer A gene 4 amino a anges Fuca B transferas 小 Figure 1.22 The ABO blood group locus codes for a B antigen Fuoo1 galactosyltransferase whose Deletion specificity determines the A blood group gene Phenotype Genotype Activity 00 No AO or AA N-Ac- gal transferase 消当 BO or BB Gal transferase N-Ac- gal& gal-transferast

Figure 1.22 The ABO blood group locus codes for a galactosyltransferase whose specificity determines the blood group. 14.1 Introduction

14.2 Breakage and reunion involves heteroduplex dna Branch migration describes the ability of a dna strand partially paired with its complement in a duplex to extend its pairing by displacing the resident strand with which it s homologous Hybrid DNA is another term for heteroduplex dna Recombinant joint is the point at which two recombining molecules of duplex dna are connected (the edge of the heteroduplex region) 消当

Branch migration describes the ability of a DNA strand partially paired with its complement in a duplex to extend its pairing by displacing the resident strand with which it is homologous. Hybrid DNA is another term for heteroduplex DNA. Recombinant joint is the point at which two recombining molecules of duplex DNA are connected (the edge of the heteroduplex region). 14.2 Breakage and reunion involves heteroduplex DNA

Progress through m eiosis M ole cular interact ion 14.2 Breakage and Leptotene M Each chrom osome has chrom somes become Sible, often Ba Oreplicated,andonsistsof 2 sister chromatids reunion involves etched to nuc A Mv heteroduplex dna Chromosom es begin AM Intiation pairing in lim ited Figure 14.1 Recombination occurs region or regions NN during the first meiotic prophase The stages of prophase are defined Pachytene by the appearance of the Synaptonem al /A Strand exchange complex extends vA Single strands exchange chromosomes. each of which along entire length of paired chromosomes A MVM consists of two replicas(sister chromatids), although the Chromosom es Nv Assimilation duplicated state becomes visible separate but are held Region of exchanged MM strands is extended only at the end. The molecular chiasmata 及 AA interactions of any individual crossing-over event involve two of Cibimoson AV Resolution the four duplex dnas condense. detach AWV from envelope chromatids become 消当

Figure 14.1 Recombination occurs during the first meiotic prophase. The stages of prophase are defined by the appearance of the chromosomes, each of which consists of two replicas (sister chromatids), although the duplicated state becomes visible only at the end. The molecular interactions of any individual crossing-over event involve two of the four duplex DNAs. 14.2 Breakage and reunion involves heteroduplex DNA

HHHHHHHHH 14.2 Breakage and DNA duplexes pair reunion involves HHHHHHH heteroduplex dna HHHH Broken strands exchange between duplexes Figure 14.2 Cro ssover point moves Recombination between Second nicks made in same strand Second nicks made in other strand two paired duplex dna HHHHHHH HHHHHHHHHHHHH HHHHHH could involve reciprocal single-strand exchange branch migration, and HHHHHHHHHHHHI exes, and nic年 nicki nnnnnn gnomes are not recombinant Reciprocal recombinant 消当 t contain heteroduplex region genomes are generated TLLLLHHHH

Figure 14.2 Recombination between two paired duplex DNAs could involve reciprocal single-strand exchange, branch migration, and nicking. 14.2 Breakage and reunion involves heteroduplex DNA

14.2 Breakage and reunion involves heteroduplex dna Figure 14. 3 Branch migration can occur in either direction when an unpaired single strand displaces a paired strand 消当

Figure 14.3 Branch migration can occur in either direction when an unpaired single strand displaces a paired strand. 14.2 Breakage and reunion involves heteroduplex DNA

14.2 Breakage and reunion involves Rotation shows structure heteroduplex dna of Holliday junction Figure 14.4 Resolution of a holliday junction can generate parental or recombinant duplexes depending on which Nic king controls out come strands are nicked. Both Nicks in other strand Nicks in same release splice strands recom binants release patch types of product have a (conventional recom binants region of heteroduplex DNA 某k 消当

Figure 14.4 Resolution of a Holliday junction can generate parental or recombinant duplexes, depending on which strands are nicked. Both types of product have a region of heteroduplex DNA. 14.2 Breakage and reunion involves heteroduplex DNA