title: Double-strand break repair and recombination-dependent replication of DNA in bacteriophage T4 in the absence of UvsX recombinase: replicative resolution pathway.
abstract: The effects of mutations in bacteriophage T4 genes uvsX and 49 on the double-strand break (DSB)-promoted recombination were studied in crosses, in which DSBs were induced site-specifically within the rIIB gene by SegC endonuclease in the DNA of only one of the parents. Frequency of rII+ recombinants was measured in two-factor crosses of the type i×ets1 and in three-factor crosses of the type i×ets1 a6, where ets1 is an insertion in the rIIB gene carrying the cleavage site for SegC; i's are rIIB or rIIA point mutations located at various distances (12-2040 bp) from the ets1 site, and a6 is rIIA point mutation located at 2040 bp from ets1. The frequency/distance relationships were obtained in crosses of the wild-type phage and of the amber mutant S17 (gene uvsX) and the double mutant S17 E727 (genes uvsX and 49). These data provide information about the frequency and distance distribution of the single-exchange (splices) and double-exchange (patches) events. The extended variant of the splice/patch coupling (SPC) model of recombination, which includes transition to the replication resolution (RR) alternative is substantiated and used for interpretation of the frequency/distance relationships. We conclude that the uvsX mutant executes recombination-dependent replication but does it by a qualitatively different way. In the absence of UvsX function, the DSB repair runs largely through the RR subpathway because of inability of the mutant to form a Holliday junction. In the two-factor crosses, the double uvsX 49- is recombinationally more proficient than the single uvsX mutant (partial suppression of the uvsX deficiency), while the patch-related double exchanges are virtually eliminated in this background.
authors.affiliation: Institute of Problems of Chemical Physics RAS, Chernogolovka, Moscow Region 142432, Russia. svp@icp.ac.ru
authors.forename: Victor P
authors.initials: VP
authors.lastname: Shcherbakov
authors.forename: Lidia
authors.initials: L
authors.lastname: Plugina
authors.forename: Tamara
authors.initials: T
authors.lastname: Shcherbakova
authors.forename: Elena
authors.initials: E
authors.lastname: Kudryashova
authors.forename: Svetlana
authors.initials: S
authors.lastname: Sizova
mesh_terms: D017122:Bacteriophage T4 / Q000235:genetics* / Q000378:metabolism*; D003433:Crosses, Genetic; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000378:metabolism*; D023061:Gene Order; D008565:Membrane Proteins / Q000378:metabolism*; D008957:Models, Genetic; D009154:Mutation; D011938:Rec A Recombinases / Q000378:metabolism; D011995:Recombination, Genetic; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D008565:Membrane Proteins; C092863:UvsX protein, Enterobacteria phage T4; D014764:Viral Proteins; D011938:Rec A Recombinases