Identification of an Escherichia coli operon required for formation of the O-antigen capsule.
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.
Peleg
Adi
A
Department of Molecular Genetics and Biotechnology, Faculty of Medicine, The Hebrew University, POB 12272, Jerusalem 91120, Israel.
Shifrin
Yulia
Y
Ilan
Ophir
O
Nadler-Yona
Chen
C
Nov
Shani
S
Koby
Simi
S
Baruch
Kobi
K
Altuvia
Shoshy
S
Elgrably-Weiss
Maya
M
Abe
Cecilia M
CM
Knutton
Stuart
S
Saper
Mark A
MA
Rosenshine
Ilan
I
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
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C120614:Etk protein, E coli; D008565:Membrane Proteins; D019081:O Antigens; D011505:Protein-Tyrosine Kinases