title: The nucleotide excision repair (NER) system of Helicobacter pylori: role in mutation prevention and chromosomal import patterns after natural transformation.
abstract: BACKGROUND
  Extensive genetic diversity and rapid allelic diversification are characteristics of the human gastric pathogen Helicobacter pylori, and are believed to contribute to its ability to cause chronic infections. Both a high mutation rate and frequent imports of short fragments of exogenous DNA during mixed infections play important roles in generating this allelic diversity. In this study, we used a genetic approach to investigate the roles of nucleotide excision repair (NER) pathway components in H. pylori mutation and recombination.
  
  
  RESULTS
  Inactivation of any of the four uvr genes strongly increased the susceptibility of H. pylori to DNA damage by ultraviolet light. Inactivation of uvrA and uvrB significantly decreased mutation frequencies whereas only the uvrA deficient mutant exhibited a significant decrease of the recombination frequency after natural transformation. A uvrC mutant did not show significant changes in mutation or recombination rates; however, inactivation of uvrC promoted the incorporation of significantly longer fragments of donor DNA (2.2-fold increase) into the recipient chromosome. A deletion of uvrD induced a hyper-recombinational phenotype.
  
  
  CONCLUSIONS
  Our data suggest that the NER system has multiple functions in the genetic diversification of H. pylori, by contributing to its high mutation rate, and by controlling the incorporation of imported DNA fragments after natural transformation.
authors.affiliation: Institute of Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Hannover, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Moccia
authors.forename: Juliane
authors.initials: J
authors.lastname: Krebes
authors.forename: Stefan
authors.initials: S
authors.lastname: Kulick
authors.forename: Xavier
authors.initials: X
authors.lastname: Didelot
authors.forename: Christian
authors.initials: C
authors.lastname: Kraft
authors.forename: Christelle
authors.initials: C
authors.lastname: Bahlawane
authors.forename: Sebastian
authors.initials: S
authors.lastname: Suerbaum
mesh_terms: D004260:DNA Repair; D045643:DNA Repair Enzymes / Q000235:genetics; D017353:Gene Deletion; D014644:Genetic Variation; D016480:Helicobacter pylori / Q000201:enzymology* / Q000235:genetics* / Q000502:physiology; D006801:Humans; D009154:Mutation; D059645:Mutation Rate; D011995:Recombination, Genetic; D014169:Transformation, Bacterial
chemical_list: D045643:DNA Repair Enzymes