Colanic Acid

Goebel, Walther F.

doi:10.1073/pnas.49.4.464

Cited by 65 publications

(45 citation statements)

References 6 publications

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“…Goebel (11) (19). However, we were unable to detect the group II K antigen in the (cell-free) extracellular polysaccharide fraction from these strains, which suggests that if K antigen was made it was retained on the cell surface as a capsular layer.…”

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Coexpression of colanic acid and serotype-specific capsular polysaccharides in Escherichia coli strains with group II K antigens

et al. 1993

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In Escherichia coli K-12, the rcsA and rcsB gene products are positive regulators in expression of the slime polysaccharide colanic acid. We have previously demonstrated the presence of rcsA sequences in E. coli Kl and K5, strains with group II capsular K antigens, and shown that introduction of multicopy rcsA into these strains results in the expression of colanic acid. We report here the presence of rcsB sequences in E. coli Kl and K5 and demonstrate that RcsB also plays a role in the biosynthesis of colanic acid in strains with group II K antigens. In E. coli Ki and K5 grown at 37rC, multicopy rcsB and the resulting induction of colanic acid synthesis had no significant effect on synthesis of the group II K antigens. K-antigen-specific sugar transferase activities were not significantly different in the presence or absence of multicopy rcsB, and introduction of a cps mutation to eliminate colanic acid biosynthesis in a Kl-derivative strain did not influence the activity of the polysialyltransferase enzyme responsible for synthesis of the Kl polymer. Furthermore, immunoelectron microscopy showed no detectable difference in the size or distribution of the group II K-antigen capsular layer in cells which produced colanic acid. Colanic acid expression therefore does not appear to significantly affect synthesis of the group II K-antigen capsule and, unlike for group I K antigens, expression of group II K antigens is not positively regulated by the rcs system. Escherichia coli produces a variety of cell surface polysaccharides. The LPS 0 antigens and capsular K antigens of E. coli are structurally heterogeneous and are major determinants of serotype specificity and pathogenicity (27). Colanic acid (M antigen) is an extracellular slime polysaccharide. This polymer is not serotype specific and is produced under the appropriate growth conditions by several strains of E. coli, as well as by a number of other members of the family Enterobacteriaceae (22). Colanic acid does not appear to be involved in pathogenesis, and its precise function is not clear. However, it has been speculated that colanic acid may protect the cell under conditions of membrane perturbation (28) or dessication (26).The regulation of colanic acid gene expression has been characterized in E. coli K-12 (see reference 12 for a review). Transcription of the cps (colanic acid biosynthesis) gene cluster is regulated by three positive regulators (RcsA, RcsB, and RcsF) and two negative regulators (RcsC and Lon). On the basis of sequence homologies with other systems, RcsC and RcsB are thought to be the sensor and effector, respectively, of a two-component regulatory system (32). A recent report (9) proposed that RcsF activates RcsB; activation may occur through kinase activity, although phosphorylation has not been directly demonstrated. In this case, RcsC may modulate the activity of RcsB by phosphatase activity (9). RcsA is believed to act as an auxiliary factor, apparently exerting its effect by forming a heterodimer with RcsB to increase transcription...

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confidence: 68%

Coexpression of colanic acid and serotype-specific capsular polysaccharides in Escherichia coli strains with group II K antigens

et al. 1993

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“…The specific capsules are called K antigens, and over 70 biochemically distinct polysaccharide structures have been identified (20). The nonspecific capsule is called colanic acid (or M antigen) and is produced by many enteric bacteria (11). Because colanic acid appears to be loosely attached to cells, in the past it has been designated as a slime rather than a capsule.…”

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Identification of the promoter region for the colanic acid polysaccharide biosynthetic genes in Escherichia coli K-12

Stout

1996

J Bacteriol

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The colanic acid polysaccharide capsule biosynthetic genes (cps genes) are primarily clustered at one site located at about 45 min on the Escherichia coli chromosome. The network of proteins involved in regulating the expression of these genes includes the two positive regulators RcsA and RcsB. This work describes the site of action of these two activator proteins and the promoter of the cps genes. It is likely that the cps genes are arranged in a single long operon that is at least 13.5 kb. The promoter region was identified with fusions to lacZ that resulted in regulated expression by the Rcs network of regulatory proteins, and the start site of transcription was identified by primer extension. The operator region was cloned from Kohara phage to multicopy plasmids and identified by titrating RcsA or RcsB. Sequence analysis of the promoter and operator region revealed homology to the JUMPstart element found in the untranslated region of many exopolysaccharide biosynthetic operons. In addition, the deduced amino acid sequence of the amino terminus of the first open reading frame of the cps operon was found to be homologous to proteins encoded by the exopolysaccharide biosynthetic operons of Klebsiella pneumoniae and Erwinia amylovora.

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“…Under appropriate growth conditions, E. coli K-12 strains and several other enteric bacteria produce a slime polysaccharide called colanic acid, or M antigen (18,21). Other E. coli strains, particularly clinical isolates, produce capsules (K antigens).…”

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The rcsA gene of Escherichia coli O9:K30:H12 is involved in the expression of the serotype-specific group I K (capsular) antigen

et al. 1992

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Colanic Acid

Cited by 65 publications

References 6 publications

Coexpression of colanic acid and serotype-specific capsular polysaccharides in Escherichia coli strains with group II K antigens

Coexpression of colanic acid and serotype-specific capsular polysaccharides in Escherichia coli strains with group II K antigens

Identification of the promoter region for the colanic acid polysaccharide biosynthetic genes in Escherichia coli K-12

The rcsA gene of Escherichia coli O9:K30:H12 is involved in the expression of the serotype-specific group I K (capsular) antigen

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