title: Genetic variation at the O-antigen biosynthetic locus in Pseudomonas aeruginosa.
abstract: The outer carbohydrate layer, or O antigen, of Pseudomonas aeruginosa varies markedly in different isolates of these bacteria, and at least 20 distinct O-antigen serotypes have been described. Previous studies have indicated that the major enzymes responsible for O-antigen synthesis are encoded in a cluster of genes that occupy a common genetic locus. We used targeted yeast recombinational cloning to isolate this locus from the 20 internationally recognized serotype strains. DNA sequencing of these isolated segments revealed that at least 11 highly divergent gene clusters occupy this region. Homology searches of the encoded protein products indicated that these gene clusters are likely to direct O-antigen biosynthesis. The O15 serotype strains lack functional gene clusters in the region analyzed, suggesting that O-antigen biosynthesis genes for this serotype are harbored in a different portion of the genome. The overall pattern underscores the plasticity of the P. aeruginosa genome, in which a specific site in a well-conserved genomic region can be occupied by any of numerous islands of functionally related DNA with diverse sequences.
authors.affiliation: University of Washington Genome Center, Department of Medicine, University of Washington, Seattle, Washington 98195, USA. craymond@u.washington.edu
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Raymond
authors.forename: Elizabeth H
authors.initials: EH
authors.lastname: Sims
authors.forename: Arnold
authors.initials: A
authors.lastname: Kas
authors.forename: David H
authors.initials: DH
authors.lastname: Spencer
authors.forename: Tanya V
authors.initials: TV
authors.lastname: Kutyavin
authors.forename: Richard G
authors.initials: RG
authors.lastname: Ivey
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhou
authors.forename: Rajinder
authors.initials: R
authors.lastname: Kaul
authors.forename: James B
authors.initials: JB
authors.lastname: Clendenning
authors.forename: Maynard V
authors.initials: MV
authors.lastname: Olson
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D017124:Conserved Sequence; D014644:Genetic Variation; D008969:Molecular Sequence Data; D019081:O Antigens / Q000096:biosynthesis* / Q000235:genetics; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000378:metabolism; D015003:Yeasts / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D019081:O Antigens; C095976:O antigen, Pseudomonas