title: Phenotypic and genotypic variation in methylases involved in type II restriction-modification systems in Helicobacter pylori.
abstract: To determine relationships between Helicobacter pylori geographical origin and type II methylase activity, we examined 122 strains from various locations around the world for methylase expression. Most geographic regions possessed at least one strain resistant to digestion by each of 14 restriction endonucleases studied. Across all of the strains studied, the average number of active methylases was 8.2 +/- 1.9 with no significant variation between the major geographic regions. Although seven pairs of isolates showed the same susceptibility patterns, their cagA/vacA status differed, and the remaining 108 strains each possessed unique patterns of susceptibility. From a single clonal group, 15 of 18 strains showed identical patterns of resistance, but diverged with respect to M.MboII activity. All of the methylases studied were present in all major human population groupings, suggesting that their horizontal acquisition pre-dated the separation of these populations. For the hpyV and hpyAIV restriction-modification systems, an in-depth analysis of genotype, indicating extensive diversity of cassette size and chromosomal locations regardless of the susceptibility phenotype, points toward substantial strain-specific selection involving these loci.
authors.affiliation: Department of Medicine, New York University School of Medicine, New York, NY 10016, USA. takattol@cis.fukuoka-u.ac.jp
authors.forename: Tohru
authors.initials: T
authors.lastname: Takata
authors.forename: Rahul
authors.initials: R
authors.lastname: Aras
authors.forename: Donald
authors.initials: D
authors.lastname: Tavakoli
authors.forename: Takafumi
authors.initials: T
authors.lastname: Ando
authors.forename: Asalia Z
authors.initials: AZ
authors.lastname: Olivares
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Blaser
mesh_terms: D000942:Antigens, Bacterial; D001426:Bacterial Proteins / Q000235:genetics; D015139:Blotting, Southern; D015254:DNA Modification Methylases / Q000235:genetics* / Q000378:metabolism*; D015252:Deoxyribonucleases, Type II Site-Specific / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial / Q000235:genetics; D014644:Genetic Variation / Q000235:genetics*; D005838:Genotype; D005843:Geography; D016480:Helicobacter pylori / Q000145:classification / Q000201:enzymology* / Q000235:genetics*; D010641:Phenotype; D016133:Polymerase Chain Reaction; D013045:Species Specificity
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C074689:VacA protein, Helicobacter pylori; C080866:cagA protein, Helicobacter pylori; D015254:DNA Modification Methylases; D015252:Deoxyribonucleases, Type II Site-Specific