Glutamic acid-112 of the A subunit of heat-labile enterotoxin from enterotoxigenic Escherichia coli is important for ADP-ribosyltransferase activity.
A mutant strain of enterotoxigenic Escherichia coli (E. coli pTUH 6A) produced an abnormal heat-labile enterotoxin (LT), the A subunit of which has a single amino acid substitution at position 112 (Glu-112 to Lys-112). As already reported, this mutant LT had no ileal loop and vascular permeability activities [(1990) J. Biol. Chem. 265, 22520-22525]. In this paper we report that the mutant LT showed no CHO cell elongation activity and did not activate adenylate cyclase of target cells. Moreover, no ADP-ribosyltransferase activity was detected in the mutant LT. It is concluded that the amino acid substitution at position 112 abolished the ADP-ribosyltransferase activity of the A subunit and this leads to the loss of toxic activities of LT.
Department of the Microbiology, Fujita Health University School of Medicine, Aichi, Japan.
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Tsuji
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Inoue
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Miyama
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Noda
D000595:Amino Acid Sequence; D000818:Animals; D001427:Bacterial Toxins / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology; D001681:Biological Assay; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000737:chemistry; D004768:Enterotoxins / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins; D005971:Glutamates / Q000737:chemistry*; D018698:Glutamic Acid; D016296:Mutagenesis; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism* / Q000494:pharmacology
D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D005971:Glutamates; D018698:Glutamic Acid; C027538:heat-labile enterotoxin, E coli; D000242:Cyclic AMP; D011065:Poly(ADP-ribose) Polymerases