title: Sequence analysis of four Shigella boydii O-antigen loci: implication for Escherichia coli and Shigella relationships.
abstract: Shigella strains are in reality clones of Escherichia coli and are believed to have emerged relatively recently (G. M. Pupo, R. Lan, and P. R. Reeves, Proc. Natl. Acad. Sci. USA 97:10567-10572, 2000). There are 33 O-antigen forms in these Shigella clones, of which 12 are identical to O antigens of other E. coli strains. We sequenced O-antigen gene clusters from Shigella boydii serotypes 4, 5, 6, and 9 and also studied the O53- and O79-antigen gene clusters of E. coli, encoding O antigens identical to those of S. boydii serotype 4 and S. boydii serotype 5, respectively. In both cases the S. boydii and E. coli O-antigen gene clusters have the same genes and organization. The clusters of both S. boydii 6 and S. boydii 9 O antigens have atypical features, with a functional insertion sequence and a wzx gene located in the orientation opposite to that of all other genes in S. boydii serotype 9 and an rmlC gene located away from other rml genes in S. boydii serotype 6. Sequences of O-antigen gene clusters from another three Shigella clones have been published, and two of them also have abnormal structures, with either the entire cluster or one gene being located on a plasmid in Shigella sonnei or Shigella dysenteriae, respectively. It appears that a high proportion of clusters coding for O antigens specific to Shigella clones have atypical features, perhaps indicating recent formation of these gene clusters.
authors.affiliation: Department of Microbiology, The University of Sydney, Sydney, New South Wales 2006, Australia.
authors.forename: L
authors.initials: L
authors.lastname: Wang
authors.forename: W
authors.initials: W
authors.lastname: Qu
authors.forename: P R
authors.initials: PR
authors.lastname: Reeves
mesh_terms: D001426:Bacterial Proteins; D001483:Base Sequence; D002237:Carbohydrate Dehydrogenases / Q000235:genetics; D002238:Carbohydrate Epimerases / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics; D004269:DNA, Bacterial / Q000032:analysis; D004926:Escherichia coli / Q000145:classification* / Q000235:genetics; D005798:Genes, Bacterial; D006156:Guanosine Diphosphate Sugars / Q000096:biosynthesis; D006602:Hexosyltransferases / Q000235:genetics; D006836:Hydro-Lyases / Q000235:genetics; D008359:Mannose-6-Phosphate Isomerase / Q000235:genetics; D008361:Mannosidases / Q000235:genetics; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics; D005810:Multigene Family; D009702:Nucleoside Diphosphate Sugars / Q000096:biosynthesis; D009713:Nucleotidyltransferases / Q000235:genetics; D019081:O Antigens / Q000235:genetics*; D017422:Sequence Analysis, DNA; D012760:Shigella / Q000235:genetics; D012761:Shigella boydii / Q000145:classification / Q000235:genetics*; D013942:Thymine Nucleotides / Q000096:biosynthesis; D044902:beta-Mannosidase
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; C422949:GDP-rhamnose; D006156:Guanosine Diphosphate Sugars; D008565:Membrane Proteins; D009097:Multienzyme Complexes; D009702:Nucleoside Diphosphate Sugars; D019081:O Antigens; C117254:RfbX protein, Pseudomonas; D013942:Thymine Nucleotides; C073293:thymidine diphosphate rhamnose; D002237:Carbohydrate Dehydrogenases; C107144:dTDP-4-dehydrorhamnose reductase; D006602:Hexosyltransferases; C085652:O-antigen polymerase; C093300:ManB protein, bacteria; D009713:Nucleotidyltransferases; C020587:glucose-1-phosphate thymidylyltransferase; D008361:Mannosidases; D044902:beta-Mannosidase; D006836:Hydro-Lyases; C022771:dTDPglucose 4,6-dehydratase; D002238:Carbohydrate Epimerases; C020092:dTDP-4-ketorhamnose 3,5-epimerase; D008359:Mannose-6-Phosphate Isomerase