title: Intramolecular chaperone activity of the pro-region of Vibrio cholerae El Tor cytolysin.
abstract: Vibrio cholerae synthesizes a toxin named El Tor cytolysin/hemolysin, which lyses erythrocytes and other mammalian cells. This toxin is encoded by the hlyA gene and is synthesized as a precursor form, prepro-HlyA. Prepro-HlyA consists of, from the amino terminus of this protein, a signal peptide, a pro-region, and a mature region. The pro-region is cleaved off extracellularly resulting in activation. To analyze the role of the pro-region, we substituted the native hlyA gene with the pro-region-deleted hlyA gene (hlyA delta pro). The hemolytic activity of the mutant organism was markedly decreased; the product of the hlyA delta pro gene, secreted in the periplasm, was degraded. To compare their abilities to form tertiary structure, the purified mature- and pro-HlyA were denatured and then renatured by reducing the concentration of denaturant; the denatured pro-HlyA recovered almost all activity while the mature-HlyA was not renatured. The sequences of the pro-region and a molecular chaperone, Hsp90, were similar. The pro-region expressed in Escherichia coli containing the hlyA delta pro gene increased the cytolytic activity. The purified pro-region peptide also facilitated renaturation of the denatured mature HlyA. These results suggest that the pro-region possibly guides the folding of the cytolysin similar to a molecular chaperone; the pro-region and molecular chaperones share common function and structure.
authors.affiliation: Department of Bacterial Infections, Research Institute for Microbial Diseases, Osaka University, Suita, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nagamune
authors.forename: K
authors.initials: K
authors.lastname: Yamamoto
authors.forename: T
authors.initials: T
authors.lastname: Honda
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D003603:Cytotoxins / Q000378:metabolism*; D018841:HSP90 Heat-Shock Proteins / Q000737:chemistry; D006460:Hemolysin Proteins / Q000737:chemistry* / Q000378:metabolism; D018832:Molecular Chaperones / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D015183:Restriction Mapping; D014734:Vibrio cholerae / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D003603:Cytotoxins; D018841:HSP90 Heat-Shock Proteins; D006460:Hemolysin Proteins; D018832:Molecular Chaperones; C084287:hlyA protein, Vibrio cholerae