Repair and antirepair DNA helicases in Helicobacter pylori.
Orthologs of RecG and RuvABC are highly conserved among prokaryotes; in Escherichia coli, they participate in independent pathways that branch migrate Holliday junctions during recombinational DNA repair. RecG also has been shown to directly convert stalled replication forks into Holliday junctions. The bacterium Helicobacter pylori, with remarkably high levels of recombination, possesses RecG and RuvABC homologs, but in contrast to E. coli, H. pylori RecG limits recombinational repair. We now show that the RuvABC pathway plays the prominent, if not exclusive, repair role. By introducing an E. coli resolvase (RusA) into H. pylori, the repair and recombination phenotypes of the ruvB mutant but not the recG mutant were improved. Our results indicate that RecG and RuvB compete for Holliday junction structures in recombinational repair, but since a classic RecG resolvase is absent from H. pylori, deployment of the RecG pathway is lethal. We propose that evolutionary loss of the H. pylori RecG resolvase provides an "antirepair" pathway allowing for selection of varied strains. Such competition between repair and antirepair provides a novel mechanism to maximize fitness at a bacterial population level.
Kang
Josephine
J
Department of Medicine, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA. kangm01@med.nyu.edu
Blaser
Martin J
MJ
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D004265:DNA Helicases / Q000235:genetics* / Q000378:metabolism; D004260:DNA Repair; D004706:Endodeoxyribonucleases / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D005816:Genetic Complementation Test; D016480:Helicobacter pylori / Q000201:enzymology / Q000235:genetics*; D045565:Holliday Junction Resolvases / Q000235:genetics / Q000378:metabolism; D008957:Models, Genetic; D011995:Recombination, Genetic
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C061260:RuvB protein, Bacteria; C069806:ruvC protein, E coli; C071446:RecG protein, E coli; D004706:Endodeoxyribonucleases; D045565:Holliday Junction Resolvases; C112057:RusA protein, E coli; C071059:Holliday junction DNA helicase, E coli; D004265:DNA Helicases