title: Role of futC slipped strand mispairing in Helicobacter pylori Lewisy phase variation.
abstract: The O antigen of the Helicobacter pylori lipopolysaccharide is composed of repeating units of fucosylated Lewis (Le) antigens. The alpha(1,2)-fucosyltransferase (futC) of H. pylori, which catalyzes the conversion of Le(x) to Le(y) by addition of fucose, is subject to slipped-strand mispairing involving a homonucleotide (poly-C) tract. To explore the distribution of Le phenotypes within H. pylori cells grown in vitro, 379 single colonies of strain J166 were examined for Le expression. Two major populations with reciprocal Le(x)/Le(y) phenotypes were identified. Phenotypes correlated with futC frame status, suggesting that strain J166 represents a mixed population with respect to futC poly-C tract length, which was confirmed by a translational reporter. After hundreds of generations in vitro, phenotypes did not change significantly, indicating that the observed J166 Le diversity reflects the founding population. Since slipped-strand mispairing in the futC poly-C tract was postulated to explain the Le(y) phenotypic change observed in J166 derivative strain 98-169 isolated 10 months after rhesus monkey challenge, in trans complementation with in-frame futC was performed. Le(y) synthesis was restored and Le(x) expression was reciprocally lowered. From these studies, we confirmed the principal role of futC slipped-strand mispairing in Le antigenic variation in vitro and in vivo.
authors.affiliation: Department of Microbiology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA.
authors.forename: Edgardo
authors.initials: E
authors.lastname: Sanabria-Valentín
authors.forename: Marie-Teresa C
authors.initials: MT
authors.lastname: Colbert
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Blaser
mesh_terms: D000818:Animals; D000940:Antigenic Variation; D001483:Base Sequence; D016368:Frameshift Mutation; D005647:Fucosyltransferases / Q000737:chemistry / Q000235:genetics*; D016481:Helicobacter Infections / Q000097:blood* / Q000382:microbiology; D016480:Helicobacter pylori / Q000235:genetics / Q000472:pathogenicity*; D006801:Humans; D007983:Lewis Blood Group Antigens / Q000235:genetics*; D008253:Macaca mulatta; D008969:Molecular Sequence Data; D011066:Poly C / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D007983:Lewis Blood Group Antigens; D011066:Poly C; D005647:Fucosyltransferases