清华大学：《分子生物学》（英文版）Chapter 15 Transposons

Chapter 15 Transposons 莘大

Chapter 15 Transposons

5.1 Introduction 15.2 Insertion sequences are simple transposition modules 5.3 Composite transposons have is modules 15.4 Transposition occurs by both replicative and nonreplicative mechanisms 15.5 Transposons cause rearrangement of dNA 5.6 Common intermediates for transposition 15.7 Replicative transposition proceeds through a cointegrate 15.8 Nonreplicative transposition proceeds by breakage and reunion 15.9 TnA transposition requires transposase and resolvase 5. 10 Transposition of Tnlo has multiple controls 15. 11 Controlling elements in maize cause breakage and rearrangements 15. 12 Controlling elements form families of transposons 15 13 Spm elements influence gene expression 15.15 P elements are activated in the germline 消当

15.1 Introduction 15.2 Insertion sequences are simple transposition modules 15.3 Composite transposons have IS modules 15.4 Transposition occurs by both replicative and nonreplicative mechanisms 15.5 Transposons cause rearrangement of DNA 15.6 Common intermediates for transposition 15.7 Replicative transposition proceeds through a cointegrate 15.8 Nonreplicative transposition proceeds by breakage and reunion 15.9 TnA transposition requires transposase and resolvase 15.10 Transposition of Tn10 has multiple controls 15.11 Controlling elements in maize cause breakage and rearrangements 15.12 Controlling elements form families of transposons 15.13 Spm elements influence gene expression 15.15 P elements are activated in the germline

15.1 Introduction Transposon is a dNa sequence able to insert itself at a new location in the genome(without any sequence relationship with the target locus) 消当

Transposon is a DNA sequence able to insert itself at a new location in the genome (without any sequence relationship with the target locus). 15.1 Introduction

15.1 Introduction Transposon is a dNa sequence able to insert itself at a new location in the genome(without any sequence relationship with the target locus) 消当

Transposon is a DNA sequence able to insert itself at a new location in the genome (without any sequence relationship with the target locus). 15.1 Introduction

15.2 Insertion sequences are simple transposition modules Direct repeats are identical (or related) sequences present in two or more copies in the same orientation in the same molecule of DNA; they are not necessarily adjacent Inverted terminal repeats are the short related or identical sequences present in reverse orientation at the ends of some transposons IS is an abbreviation for insertion sequence Transposase is the enzyme activity involved in Insertion of transposon at a new site 请莘大

Direct repeats are identical (or related) sequences present in two or more copies in the same orientation in the same molecule of DNA; they are not necessarily adjacent. Inverted terminal repeats are the short related or identical sequences present in reverse orientation at the ends of some transposons. IS is an abbreviation for insertion sequence Transposase is the enzyme activity involved in insertion of transposon at a new site. 15.2 Insertion sequences are simple transposition modules

15.2 Insertion sequences are simple transposition modules 123456789 987654321 123456789 987654321 Transposase gene Figure 15.1 Transposons have inverted terminal TACG repeats and generate direct Host dna Target site Host dNa repeats of flanking dna at the target site. In this example, the target is a 5 bi 123456789 987654321ATG ACGT123456789 987654321TAC sequence. The ends of the Target Inverted Transposon Inverted Tar epeat repeat repeat repi transposon consist of inverted repeats of 9 bp, Overall length Target selection where the numbers 1 18 bp TTT through 9 indicate a AGCN sequence of base pairs 1208 hot spots random 请莘大

Figure 15.1 Transposons have inverted terminal repeats and generate direct repeats of flanking DNA at the target site. In this example, the target is a 5 bp sequence. The ends of the transposon consist of inverted repeats of 9 bp, where the numbers 1 through 9 indicate a sequence of base pairs. 15.2 Insertion sequences are simple transposition modules

IS modules are repeated 15.3 Composite transposons have Is ISL=left ISR=nght SXTranspo son markers modules Is module has s modu le has inverted repeats inverted rep eats Figure 15.2 A composite Example transposon has a central region Tn9 IS1 cam s modules identica both function al carrying markers(such as drug resistance) flanked by Is Is modules are inverted modules. The modules have short inverted terminal repeats If the modules themselves are >Transpo son marker in inverted orientation(as Transposon Left end Markers Right end Tn903|s903 r both Is ends drawn), the short inverted functional terminal repeats at the ends of nonfunctional ter Tn10 IS1OL IS1OR funct ona the transposon are identical Tn5 S50L kar IS50R nonfunctional 消当 functional

Figure 15.2 A composite transposon has a central region carrying markers (such as drug resistance) flanked by IS modules. The modules have short inverted terminal repeats. If the modules themselves are in inverted orientation (as drawn), the short inverted terminal repeats at the ends of the transposon are identical. 15.3 Composite transposons have IS modules

15.3 Composite transposons have Is modules Transposon integrates into circular DNA Figure 15.3 Two IS10 modules create a composite transposon that s10 A ISlOR can mobilize any region of dna that lies between Outcome 1 them. When Tn10 is part of a small circular Tn10 transposon moves again molecule. the IS10 Outcome 2 repeats can transpose either side of the circle New transposon created by mobilization of is 10 modules in altemative orientation 请莘大

Figure 15.3 Two IS10 modules create a composite transposon that can mobilize any region of DNA that lies between them. When Tn10 is part of a small circular molecule, the IS10 repeats can transpose either side of the circle. 15.3 Composite transposons have IS modules

1 5.4 Transposition occurs by both replicative and nonreplicative mechanisms Conservative transposition refers to the movement of large elements originally classified as transposons, but now considered to be episomes The mechanism of movement resembles that of phage lambda Nonreplicative transposition describes the movement of a transposon that leaves a donor site (usually generating a double-strand break) and moves to a new site Replicative transposition describes the movement of a transposon by a mechanism in which first it is replicated, and then one copy is transferred to a new site Resolvase is enzyme activity involved in site-specific recombination between two transposons present as direct repeats in a cointegrate structure Transposase is the enzyme activity involved in insertion of transposon at a new site 请莘大

Conservative transposition refers to the movement of large elements, originally classified as transposons, but now considered to be episomes. The mechanism of movement resembles that of phage lambda. Nonreplicative transposition describes the movement of a transposon that leaves a donor site (usually generating a double-strand break) and moves to a new site. Replicative transposition describes the movement of a transposon by a mechanism in which first it is replicated, and then one copy is transferred to a new site. Resolvase is enzyme activity involved in site-specific recombination between two transposons present as direct repeats in a cointegrate structure. Transposase is the enzyme activity involved in insertion of transposon at a new site. 15.4 Transposition occurs by both replicative and nonreplicative mechanisms

15. 4 Transposition occurs by both replicative and Target site nonreplicative mechanisms Figure 15. 4 The direct Staggered HHHHH HHHHHH nicks repeats of target dNA made at tar ge flanking a transposon ATGCA site are generated by the +++++4++++++++ Transposon joined to introduction of TACT single-strande end staggered cuts whose JAEC(IGEA protruding ends are Gaps at linked to the HHHHHHHHHHHHHHHHHHH target site transposon filled in anget repeats and sealed 请莘大

Figure 15.4 The direct repeats of target DNA flanking a transposon are generated by the introduction of staggered cuts whose protruding ends are linked to the transposon. 15.4 Transposition occurs by both replicative and nonreplicative mechanisms