PMID:15598734
| Citation |
Fischbach, MA, Lin, H, Liu, DR and Walsh, CT (2005) In vitro characterization of IroB, a pathogen-associated C-glycosyltransferase. Proc. Natl. Acad. Sci. U.S.A. 102:571-6 |
|---|---|
| Abstract |
Pathogenic strains of Escherichia coli and Salmonella enterica modify the tricatecholic siderophore enterobactin (Ent) by glucosylation of three aryl carbon atoms, a process controlled by the iroA locus [Hantke, K., Nicholson, G., Rabsch, W. & Winkelmann, G. (2003) Proc. Natl. Acad. Sci. USA 100, 3677-3682]. Here, we report the purification of the IroB protein and its characterization as the Ent C-glucosyltransferase. IroB transfers glucosyl groups from uridine-5'-diphosphoglucose to C5 of one, two, or three of the 2,3-dihydroxybenzoyl units of Ent to yield monoglucosyl-C-Ent (MGE), diglucosyl-C-Ent (DGE), and triglucosyl-C-Ent (TGE). DGE, also known as salmochelin S4, and macrolactone-opened derivatives have been isolated from the culture broths of S. enterica and uropathogenic E. coli [Bister, B., Bischoff, D., Nicholson, G. J., Valdebenito, M., Schneider, K., Winkelmann, G., Hantke, K. & Sussmuth, R. D. (2004) Biometals 17, 471-481], but MGE and TGE have not been reported previously. IroB has a k(cat) of approximately 10 min(-1) for the first C-glucosylation and is distributive, with sequential conversion and buildup of MGE and then DGE. The C5 to C1' regio-selectivity of the 2,3-dihydroxybenzoyl-glucose linkage at all three rings of TGE suggests a C5 carbanion, para to the C2 phenolate oxygen, as the carbon nucleophile in this novel enzymatic C-glucosylation. |
| Links |
PubMed PMC545562 Online version:10.1073/pnas.0408463102 |
| Keywords |
Cloning, Molecular/methods; Enterobactin/metabolism; Escherichia coli Proteins/chemistry; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Glucosyltransferases/chemistry; Glucosyltransferases/genetics; Glucosyltransferases/metabolism; Glycosylation; Glycosyltransferases/chemistry; Glycosyltransferases/genetics; Glycosyltransferases/metabolism; Kinetics; Uridine Diphosphate Glucose/metabolism |
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