Affiliation:
1. Department of Bacterial Infections, Research Institute for Microbial Diseases, Osaka University, Suita, Japan.
Abstract
Vibrio cholerae produces a cytolytic toxin named El Tor cytolysin/hemolysin which is encoded by the hlyA gene. This cytolysin is produced as a 79-kDa precursor form (pro-HlyA) into the culture supernatant after cleavage of the signal peptide of the hlyA product (prepro-HlyA). The pro-HlyA is then processed to a 65-kDa mature cytolysin (mature HlyA) after cleavage of the 15-kDa N-terminal peptide (pro region) of the 79-kDa precursor, usually at the bond between Ala-157 and Asn-158. We investigated whether proteases could process the recombinant 79-kDa pro-HlyA to the 65-kDa mature HlyA. We observed that the soluble hemagglutinin/ protease (HA/protease; a major protease of V. cholerae), trypsin, alpha-chymotrypsin, subtilisin BPN', papain, and thermolysin all processed the pro-HlyA to the 65-kDa mature form of the protein. Along with this, the protease-processed HlyA showed drastically increased hemolytic activity. The N-terminal amino acid of the mature form of cytolysin generated by HA/protease was Phe-151, and that due to trypsin was Ser-149. Other proteases also cleaved the pro-HlyA at a nearby site, between Leu-146 and Ser-153, and all the processed cytolysins showed increased hemolytic activity. These data suggest that the active El Tor cytolysin of V. cholerae could be derived from the C-terminal region of a pro-HlyA following proteolytic cleavage of the bonds in the vicinity of Leu-146 to Asn-158 by any of a wide variety of proteases.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
83 articles.
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