title: Regulation of Helicobacter pylori adherence by gene conversion.
abstract: Genetic diversification of Helicobacter pylori adhesin genes may allow adaptation of adherence properties to facilitate persistence despite host defences. The sabA gene encodes an adhesin that binds sialyl-Lewis antigens on inflamed gastric tissue. We found variability in the copy number and locus of the sabA gene and the closely related sabB and omp27 genes due to gene conversion among 51 North American paediatric H. pylori strains. We determined that sabB to sabA gene conversion is predominantly the result of intra-genomic recombination and RecA, RecG and AddA influence the rate at which it occurs. Although all clinical strains had at least one sabA gene copy, sabA and sabB were lost due to gene conversion at similar rates in vitro, suggesting host selection to maintain the sabA gene. sabA gene duplication resulted in increased SabA protein production and increased adherence to sialyl-Lewis antigens and mouse gastric tissue. In conclusion, gene conversion is a mechanism for H. pylori to regulate sabA expression level and adherence.
authors.affiliation: Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Talarico
authors.forename: Shawn E
authors.initials: SE
authors.lastname: Whitefield
authors.forename: Jutta
authors.initials: J
authors.lastname: Fero
authors.forename: Rainer
authors.initials: R
authors.lastname: Haas
authors.forename: Nina R
authors.initials: NR
authors.lastname: Salama
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D001422:Bacterial Adhesion; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D005753:Gastric Mucosa / Q000382:microbiology; D005785:Gene Conversion; D018628:Gene Dosage; D016481:Helicobacter Infections / Q000382:microbiology; D016480:Helicobacter pylori / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity / Q000502:physiology*; D006801:Humans; D007983:Lewis Blood Group Antigens / Q000378:metabolism; D051379:Mice; D012641:Selection, Genetic
chemical_list: D018829:Adhesins, Bacterial; D001425:Bacterial Outer Membrane Proteins; D007983:Lewis Blood Group Antigens; C500808:SabA protein, Helicobacter pylori