Recombinational Repair of DNA Damage in Escherichia coli and Bacteriophage l

TWO-STRAND DNA DAMAGE, RECOMBINATIONAL REPAIR, SOS RESPONSE, AND DNA REPLICATION ...................................................................................................................................................753 Mechanisms of DNA Damage and Repair ..........................................................................................................753 Damage reversal and one-strand repair..........................................................................................................753 Two-strand repair ...............................................................................................................................................753 Homologous recombination versus recombinational repair .........................................................................754 The two mechanisms of two-strand damage ...................................................................................................755 The two recombinational repair pathways of E. coli .....................................................................................755 Frequency of two-strand lesions .......................................................................................................................756 Recombinational repair capacity of E. coli cells ............................................................................................756 SOS Response: Reaction of E. coli to DNA Damage .........................................................................................756 Repair instead of DNA damage checkpoints: the prokaryotic strategy ......................................................756 Organization of the SOS regulon .....................................................................................................................757 Levels of SOS induction.....................................................................................................................................758 Cellular Processes That Surround and Complicate Recombinational Repair...............................................758 Initiation of chromosomal DNA replication in E. coli...................................................................................759 Elongation phase of DNA replication in E. coli .............................................................................................759 Initiation of plasmid DNA replication.............................................................................................................759 Nucleoid segregation and the problem of accessibility .................................................................................760 Summary ..................................................................................................................................................................760 RecA: HOMOLOGOUS PAIRING ACTIVITY .......................................................................................................760 recA Gene and Mutants .....................................................................................................................................760 recA and peculiarities of recA null mutants ....................................................................................................760 Cellular processes dependent on RecA............................................................................................................760 In Vitro Activities of RecA.....................................................................................................................................761 RecA without DNA..............................................................................................................................................761 Filament formation by RecA around ssDNA ..................................................................................................761 Two DNA-binding sites in RecA filament........................................................................................................761 Cleavage of LexA repressor by RecA filament................................................................................................763 Detection by RecA filament of homology to ssDNA bound in the primary site ........................................763 Strand exchange between DNA1 and DNA2 catalyzed by RecA filament...................................................764 Assistance for RecA by SSB at all stages........................................................................................................764 Supervision of RecA Activity .................................................................................................................................765 Inhibition by MutS and MutL of pairing between homeologous sequences ..............................................765 Possible disruption of pairing of insufficient length by helicase II.............................................................765 Summary ..................................................................................................................................................................766 RESOLVING RECOMBINATION INTERMEDIATES ........................................................................................766 The Three Ways To Remove a Pair of DNA Junctions. ....................................................................................766 ruv Locus: Phenotypes of Mutants and Genetic Structure ...............................................................................766 Interaction of Ruv Proteins In Vitro with Holliday Junctions.........................................................................767 Pairwise Interactions of Ruv Proteins: RuvABC Resolvasome ........................................................................768 RuvAB Translocase.................................................................................................................................................769 RecG Helicase..........................................................................................................................................................770 Three-Strand Junctions and the Hypothetical RecG Pathway.........................................................................770 Summary ..................................................................................................................................................................770 REPAIR OF DAUGHTER STRAND GAPS............................................................................................................770 Origin of Daughter Strand Gaps and Mechanism of Their Repair: Early Studies ......................................771 Presynaptic Phase of Daughter Strand Gap Repair: RecF, RecO, and RecR ...............................................772 recF, recO, and recR: mutant phenotypes ........................................................................................................772 recF, recO, and recR: possible replisome connection revealed by gene structure ......................................772 Properties of RecF, RecO, and RecR and their influence on RecA-promoted reactions in vitro ...........773