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Role of Tryptophan‐1 in Hemolytic and Phospholipase C Activities of Clostridium perfringens Alpha‐Toxin
Author(s) -
Nagahama Masahiro,
Mukai Masakazu,
Ochi Sadayuki,
Sakurai Jun
Publication year - 2000
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.2000.tb02537.x
Subject(s) - clostridium perfringens , toxin , biology , biochemistry , phospholipase c , histidine , tyrosine , mutant , amino acid , tryptophan , haemolysis , microbiology and biotechnology , receptor , bacteria , genetics , gene , immunology
Replacement of the Trp‐1 in Clostridium perfringens alpha‐toxin with tyrosine caused no effect on hemolytic and phospholipase C (PLC) activities or on binding to the zinc ion, but that of the residue with alanine, glycine and histidine led to drastic decreases in these activities and a significant reduction in binding to the zinc ion. The hemolytic and PLC activities of W1H and W1A were significantly increased by the preincubation of these variant toxins with zinc ions, but the preincubation of WIG with the metal ion caused little effect on these activities. Gly‐Ile‐alpha‐toxin, which contained an additional Gly‐Ile linked to the N‐terminal amino acid of alpha‐toxin, did not show hemolytic activity, but showed about 6% PLC activity of the wild‐type toxin. A mutant toxin, which contained an additional Gly‐Ile linked to the N‐terminus of a protein lacking 4 N‐terminal residues of alpha‐toxin, showed about 1 and 6% hemolytic and PLC activities of the wild‐type toxin, respectively. Incubation of the mutant toxin with zinc ions caused a significant increase in PLC activity. These observations suggested that Trp‐1 is not essential for toxin activity, but plays a role in binding to zinc ions.