Modulation of Vibriomimicus hemolysin through limited proteolysis by an endogenous metalloprotease

• Published in: The FEBS journal Vol. 276; no. 3; pp. 825 - 834
• Main Authors: Mizuno, Tamaki, Sultan, Syed Z, Kaneko, Yoshimi, Yoshimura, Tomonaga, Maehara, Yoko, Nakao, Hiroshi, Tsuchiya, Tomofusa, Shinoda, Sumio, Miyoshi, Shin-ichi
• Format: Journal Article
• Language: English
• Published: 01-02-2009
• ISSN: 1742-464X; 1742-4658
• DOI: 10.1111/j.1742-4658.2008.06827.x

Vibriomimicus is a causative agent of human gastroenteritis and food poisoning, and this species produces an enterotoxic hemolysin (V.mimicus hemolysin) as a virulence determinant. Vibriomimicus hemolysin is secreted as an 80kDa precursor, which is later converted to the 66kDa 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. Invitro 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 51kDa protein through removal of the C-terminal polypeptide. This 51kDa derivative was unable to lyse erythrocytes because of its inability to bind to the erythrocyte membrane. Vibriomimicus 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 that, although it is not directly related to toxin maturation invivo, V.mimicus protease can modulate the activity of V.mimicus hemolysin and/or its precursor through limited proteolysis.