title: Structural features of Escherichia coli heat-stable enterotoxin that activates membrane-associated guanylyl cyclase.
abstract: Heat-stable enterotoxin (ST), a small peptide of 18 or 19 amino acid residues produced by enterotoxigenic Escherichia coli, is the cause of acute diarrhea in infants and travelers in developing countries. ST triggers a biological response by binding to a membrane-associated guanylyl cyclase C (GC-C) which is located on intestinal epithelial cell membranes. This binding causes an increase in the concentration of cGMP as a second messenger in cells and activates protein kinase A and cystic fibrosis transmembrane conductance regulator. Here we describe the crystal structure of an ST at 0.89 A resolution. The molecule has a ring-shaped molecular architecture consisting of six peptide molecules with external and internal diameters of approximately 35 and 7 A, respectively and a thickness of approximately 11 A. The conserved residues at the central portion of ST are distributed on the outer surface of the ring-shaped peptide hexamer, suggesting that the hexamer may be implicated in the association with GC-C through these invariant residues.
authors.affiliation: Department of Applied Biological Sciences, Saga University, Saga, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Sato
authors.forename: Y
authors.initials: Y
authors.lastname: Shimonishi
mesh_terms: D000595:Amino Acid Sequence; D001427:Bacterial Toxins / Q000737:chemistry* / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology; D003460:Crystallization; D018360:Crystallography, X-Ray; D004768:Enterotoxins / Q000737:chemistry* / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins; D006162:Guanylate Cyclase / Q000378:metabolism*; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D016415:Sequence Alignment
chemical_list: D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D010455:Peptides; C034151:heat stable toxin (E coli); D006162:Guanylate Cyclase