1fgb
TOXINTOXIN
Structural highlights
FunctionCHTB_VIBCH The B subunit pentameric ring directs the A subunit to its target by binding to the GM1 gangliosides present on the surface of the intestinal epithelial cells. It can bind five GM1 gangliosides. It has no toxic activity by itself. Publication Abstract from PubMedCholera toxin, a heterohexameric AB5 enterotoxin released by Vibrio cholera, induces a profuse secretory diarrhea in susceptible hosts. Choleragenoid, the B subunit pentamer of cholera toxin, directs the enzymatic A subunit to its target by binding the GM1 gangliosides exposed on the luminal surface of intestinal epithelial cells. The crystal structure of choleragenoid has been independently solved and refined at 2.4 A resolution by combining single isomorphous replacement with non-crystallographic symmetry averaging. The structure of the B subunits, and their pentameric arrangement, closely resembles that reported for the intact holotoxin, choleragen, the heat-labile enterotoxin from Escherichia coli, and for a choleragenoid-GM1 pentasaccharide complex. In the absence of the A subunit the central cavity of the B pentamer is a highly solvated channel. The binding of choleragenoid to the A subunit or to its receptor pentasaccharide modestly affects the local stereochemistry without perceptibly altering the subunit interface. The 2.4 A crystal structure of cholera toxin B subunit pentamer: choleragenoid.,Zhang RG, Westbrook ML, Westbrook EM, Scott DL, Otwinowski Z, Maulik PR, Reed RA, Shipley GG J Mol Biol. 1995 Aug 25;251(4):550-62. PMID:7658472[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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