title: Conjugative plasmid DNA transfer in Helicobacter pylori mediated by chromosomally encoded relaxase and TraG-like proteins.
abstract: One of the striking characteristics of Helicobacter pylori is the extensive genetic diversity among clinical isolates. This diversity has been attributed to an elevated mutation rate, impaired DNA repair, DNA transfer and frequent recombination events. Plasmids have also been identified in H. pylori but it remained unknown whether conjugation can contribute to DNA transfer between clinical isolates. To examine whether H. pylori possesses intrinsic capability for conjugative plasmid transfer, shuttle vectors were introduced into H. pylori containing an oriT sequence of the conjugative IncPalpha plasmid RP4 but no mobilization (mob) genes. It was shown that these vectors could stably replicate and be mobilized among clinical H. pylori strains. It was also demonstrated that traG and relaxase (rlx) homologues carried on the H. pylori chromosome were important for plasmid transfer. Primer extension studies and mutagenesis further confirmed that the relaxase homologue rlx1 in H. pylori encodes a functional enzyme capable of acting on the RP4 oriT. Furthermore, the findings of this study indicate that traG and rlx1 act independently of the previously described type IV secretion systems, including that encoded by the cag pathogenicity island and the comB transformation apparatus, in mediating conjugative plasmid DNA transfer between H. pylori strains.
authors.affiliation: Department of Medical Microbiology, Otto von Guericke University, Leipziger Str. 44, D-39120 Magdeburg, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Backert
authors.affiliation: Department of Medical Microbiology, Otto von Guericke University, Leipziger Str. 44, D-39120 Magdeburg, Germany.
authors.forename: Terry
authors.initials: T
authors.lastname: Kwok
authors.affiliation: Department of Medical Microbiology, Otto von Guericke University, Leipziger Str. 44, D-39120 Magdeburg, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: König
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002876:Chromosomes, Bacterial / Q000235:genetics; D003227:Conjugation, Genetic; D004254:DNA Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D022761:Gene Transfer, Horizontal; D016480:Helicobacter pylori / Q000201:enzymology* / Q000235:genetics*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D010957:Plasmids / Q000235:genetics*; D014170:Transformation, Genetic
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; C073791:TraG protein, E coli; D004254:DNA Nucleotidyltransferases; C110340:DNA relaxase