title: Effect of host species on recG phenotypes in Helicobacter pylori and Escherichia coli.
abstract: Recombination is a fundamental mechanism for the generation of genetic variation. Helicobacter pylori strains have different frequencies of intragenomic recombination, arising from deletions and duplications between DNA repeat sequences, as well as intergenomic recombination, facilitated by their natural competence. We identified a gene, hp1523, that influences recombination frequencies in this highly diverse bacterium and demonstrate its importance in maintaining genomic integrity by limiting recombination events. HP1523 shows homology to RecG, an ATP-dependent helicase that in Escherichia coli allows repair of damaged replication forks to proceed without recourse to potentially mutagenic recombination. Cross-species studies done show that hp1523 can complement E. coli recG mutants in trans to the same extent as E. coli recG can, indicating that hp1523 has recG function. The E. coli recG gene only partially complements the hp1523 mutation in H. pylori. Unlike other recG homologs, hp1523 is not involved in DNA repair in H. pylori, although it has the ability to repair DNA when expressed in E. coli. Therefore, host context appears critical in defining the function of recG. The fact that in E. coli recG phenotypes are not constant in other species indicates the diverse roles for conserved recombination genes in prokaryotic evolution.
authors.affiliation: Department of Microbiology, New York University School of Medicine, VA Medical Center, New York, New York, USA. kangm01@med.nyu.edu
authors.forename: Josephine
authors.initials: J
authors.lastname: Kang
authors.forename: Don
authors.initials: D
authors.lastname: Tavakoli
authors.forename: Ariane
authors.initials: A
authors.lastname: Tschumi
authors.forename: Rahul A
authors.initials: RA
authors.lastname: Aras
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Blaser
mesh_terms: D000595:Amino Acid Sequence; D004249:DNA Damage; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005816:Genetic Complementation Test; D016680:Genome, Bacterial; D016480:Helicobacter pylori / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D010641:Phenotype; D011995:Recombination, Genetic; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
chemical_list: D029968:Escherichia coli Proteins; C071446:RecG protein, E coli; D004265:DNA Helicases