title: Identification of an Escherichia coli operon required for formation of the O-antigen capsule.
abstract: Escherichia coli produces polysaccharide capsules that, based on their mechanisms of synthesis and assembly, have been classified into four groups. The group 4 capsule (G4C) polysaccharide is frequently identical to that of the cognate lipopolysaccharide O side chain and has, therefore, also been termed the O-antigen capsule. The genes involved in the assembly of the group 1, 2, and 3 capsules have been described, but those required for G4C assembly remained obscure. We found that enteropathogenic E. coli (EPEC) produces G4C, and we identified an operon containing seven genes, ymcD, ymcC, ymcB, ymcA, yccZ, etp, and etk, which are required for formation of the capsule. The encoded proteins appear to constitute a polysaccharide secretion system. The G4C operon is absent from the genomes of enteroaggregative E. coli and uropathogenic E. coli. E. coli K-12 contains the G4C operon but does not express it, because of the presence of IS1 at its promoter region. In contrast, EPEC, enterohemorrhagic E. coli, and Shigella species possess an intact G4C operon.
authors: Department of Molecular Genetics and Biotechnology, Faculty of Medicine, The Hebrew University, POB 12272, Jerusalem 91120, Israel.
authors: Adi
authors: A
authors: Peleg
authors: Yulia
authors: Y
authors: Shifrin
authors: Ophir
authors: O
authors: Ilan
authors: Chen
authors: C
authors: Nadler-Yona
authors: Shani
authors: S
authors: Nov
authors: Simi
authors: S
authors: Koby
authors: Kobi
authors: K
authors: Baruch
authors: Shoshy
authors: S
authors: Altuvia
authors: Maya
authors: M
authors: Elgrably-Weiss
authors: Cecilia M
authors: CM
authors: Abe
authors: Stuart
authors: S
authors: Knutton
authors: Mark A
authors: MA
authors: Saper
authors: Ilan
authors: I
authors: Rosenshine
mesh_terms: D016667:Bacterial Capsules / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics; D005798:Genes, Bacterial; D008565:Membrane Proteins / Q000235:genetics; D009154:Mutation; D019081:O Antigens / Q000378:metabolism; D009876:Operon; D011505:Protein-Tyrosine Kinases / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C120614:Etk protein, E coli; D008565:Membrane Proteins; D019081:O Antigens; D011505:Protein-Tyrosine Kinases