Genetic variation at the O-antigen biosynthetic locus in Pseudomonas aeruginosa.
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.
Raymond
Christopher K
CK
University of Washington Genome Center, Department of Medicine, University of Washington, Seattle, Washington 98195, USA. craymond@u.washington.edu
Sims
Elizabeth H
EH
Kas
Arnold
A
Spencer
David H
DH
Kutyavin
Tanya V
TV
Ivey
Richard G
RG
Zhou
Yang
Y
Kaul
Rajinder
R
Clendenning
James B
JB
Olson
Maynard V
MV
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
D001426:Bacterial Proteins; D019081:O Antigens; C095976:O antigen, Pseudomonas