MSU Skol Tech Replication in bacteria

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MSU & Skol. Tech Replication in bacteria

Replication Chemistry of replication

Replication Fidelity of replication

Replication Enzymology of replication

Replication Enzymology of replication Replicative DNA polymerases DNA polymerase I + 3' exo + 5' exo 103 k. D DNA polymerase III a 130 k. D polymerase e 27 k. D 3'-exo q 9 k. D d 39 k. D c 17 k. D y 15 k. D g 48 k. D b 41 k. D processivity factor t 71 k. D

Replication Enzymology of replication Reparative DNA polymerases DNA polymerase II + 3' exo DNA polymerase IV DNA polymerase V 90 k. D 40 k. D umu. D’ umu. C’ 15 k. D 48 k. D

Replication fork

Replication Helicases

Replication Helicases closed open Rep 2 Dna. B 6

Replication Helicases Working cycle of Rep 2 Translocation Unwinding

Replication form components SSB

Replication Primase

Replication Removal of primer

Replication Ligation of Okazaki fragments

Replication Mechanism of ligation

Replication DNA polymerase III

Replication Processivity factor (clamp) Processivity factor, clamp, has pseudo 6 -fold symmetry. In E. coli b-clamp is a dimer of 3 -domain proteins Т 4 phage and eukariotes contain trimer of 2 -domain proteins (PCNA)

Replication DNA polymerase III

Replication Clamp loading

Replication Chemistry of replication

Replication Supercoiling problem ahead of replication fork

Replication Problems of concatemers resolution

Replication Similar supercoiling problems are relevant for transcription

Replication Origin of replication

Replication Initiation of replication is regulated by methylation of dam sites in ori region

Replication Initiation of replication

Replication Chemistry of replication

Replication Start of replication

Replication Termination of replication

Replication How to separate sister genomes into daughter cells? GGGNAGGG sites are located in polar fashion ori to dif Fts. K interacts with these sites and is loaded onto DNA in direction of dif Fts. K – ATPase that helps to separate genomes to daughter cells

Replication Problem of genome dimers Fts. K – ATPase that helps to separate genomes to daughter cells

Replication Problem of genome dimers Xer. C/Xer. D – recombinase is attracted to dif sites by Fts. K

Replication Problem of genome dimers Xer. C/Xer. D – recombinase

Replication Septum localization and growth

Replication Septum localization and growth Min. C inhibits Fts. Z ring polymerization Min. D interacts with Min. C, assisting its polar localization

Replication Septum localization and growth Min. C/D cap on the pole is disassembled by Min. E ring Min. C/D monomers diffuse to another pole, where they form new cap While old cap disassembles, new one is growing After complete disassembly of the old cap, Min. E ring forms on the edge of new cap As a result Min. C concentration is minimal at the midpoint of the cell, where Fts. Z could polymerize

Replication Timing of cell division Cell division time could be smaller than needed for replication of complete genome. Only frequency of replication initiation determines the doubling time.

Replication Several factors contribute to regulation of initiation of replication

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