TAILIEUCHUNG - Báo cáo khoa học: Modulation of Vibrio mimicus hemolysin through limited proteolysis by an endogenous metalloprotease

Vibrio mimicusis a causative agent of human gastroenteritis and food poisoning, and this species produces an enterotoxic hemolysin (V. mimi-cus hemolysin) as a virulence determinant. Vibrio mimicushemolysin is secreted as an 80 kDa precursor, which is later converted to the 66 kDa mature toxin through removal of an N-terminal propeptide via cleavage of the Arg151–Ser152 bond. | ỊFEBS Journal Modulation of Vibrio mimicus hemolysin through limited proteolysis by an endogenous metalloprotease Tamaki Mizuno1 Syed Z. Sultan1 Yoshimi Kaneko1 Tomonaga Yoshimura1 Yoko Maehara1 Hiroshi Nakao1 Tomofusa Tsuchiya1 Sumio Shinoda2 and Shin-ichi Miyoshi1 1 Graduate Schoolof Medicine Dentistry and PharmaceuticalSciences Okayama University Japan 2 Faculty of Science Okayama University of Science Japan Keywords hemolysin metalloprotease processing Vibrio choleras Vibrio mimicus Correspondence S. Miyoshi Graduate Schoolof Medicine Dentistry and Pharmaceutical Sciences Okayama University Tsushima-Naka Okayama 700 8530 Japan Fax 81 86 251 7926 Tel 81 86 251 7966 E-mail miyoshi@ Received 10 October 2008 revised 30 November 2008 accepted 3 December 2008 doi Vibrio mimicus is a causative agent of human gastroenteritis and food poisoning and this species produces an enterotoxic hemolysin V. mimi-cus hemolysin as a virulence determinant. Vibrio mimicus hemolysin is secreted as an 80 kDa precursor which is later converted to the 66 kDa mature toxin through removal of an N-terminal propeptide via cleavage of the Arg151-Ser152 bond. In this article we investigate the role of the endogenous metalloprotease V. mimicus protease in the maturation of V. mimicus hemolysin. In vitro experiments using purified proteins showed that although it activated the precursor at the early stage via cleavage of the Asn157-Val158 bond V. mimicus protease finally converted the activated and physiologically maturated toxin to a 51 kDa protein through removal of the C-terminal polypeptide. This 51 kDa derivative was unable to lyse erythrocytes because of its inability to bind to the erythrocyte membrane. Vibrio mimicus protease-negative strains were found to produce high levels of V. mimicus hemolysin at the logarithmic phase of bacterial growth and maintained high hemolytic activity even at the stationary phase. These findings indicate

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