title: Role of the ruvB gene in homologous and homeologous recombination in Rhizobium etli.
abstract: The Rhizobium etli ruvA and ruvB genes were cloned through a PCR-based approach, using degenerate primers matching conserved sectors in the amino acid sequences of RuvB from eight bacterial species. Comparative analysis of the predicted polypeptides for RuvA and RuvB of R. etli showed highly conserved blocks with the corresponding homologs in other bacteria; RuvB depicts characteristic motifs for DNA helicases (ATP-binding and DEXH-box motifs). An R. etli ruvB::loxP Sp mutant was constructed by interposon mutagenesis. This mutant was highly sensitive to DNA-damaging agents, such as methyl methanesulfonate and nitrofurantoin, implying a deficiency in DNA repair. Homologous and homeologous conjugational recombination was reduced almost tenfold in the ruvB::loxP Sp mutant; a recombination defect was also observed in assays employing recombination between small plasmids, albeit at a smaller magnitude. Although the ruvA and ruvB genes are contiguous in R. etli, complementation studies suggest that they are expressed independently.
authors.affiliation: Programa de Genetica Molecular de Plasmidos Bacterianos, Centro de Investigacion sobre Fijacion de Nitrogeno, Universidad Nacional Autonoma de Mexico, Apartado Postal 565-A, Cuernavaca, Morelos, Mexico.
authors.forename: J M
authors.initials: JM
authors.lastname: Martinez-Salazar
authors.forename: D
authors.initials: D
authors.lastname: Romero
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology; D003001:Cloning, Molecular; D004265:DNA Helicases / Q000235:genetics / Q000502:physiology; D004260:DNA Repair; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D029968:Escherichia coli Proteins; D008969:Molecular Sequence Data; D009154:Mutation; D011995:Recombination, Genetic; D012231:Rhizobium / Q000235:genetics* / Q000502:physiology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C061260:RuvB protein, Bacteria; C071059:Holliday junction DNA helicase, E coli; D004265:DNA Helicases