Molecular Genetic Analysis and Mechanism of Action of Bacterial Cytolysins

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This research projiects was organized to accumulate the information of property of various bacterial cytolysisns and to understand their exact role in infection. Shinoda purified Vibrio vulnificus hemolysin (VVH) and studied its property. Sensitivity of erythrocytes to VVH varied with the animal species because of difference of their ability to bind VVH. Some strains produced immunologically different VVH. Katoh and Noda studied the mechanism of cytolytic action of alpha-toxin and leukocidin of Staphylococcus aureus and found that their NAD-ribosylation activity was important to the lytic action. They also showed the exact role of S- and F-fragment of leukocidin. Sakurai found that active center for hemolytic activity and phospholipase of alpha-toxin of Clostridium perfrigens located on different sites of the toxin molecule. Furthermore, he showed change of phospholipid metabolism in action of the toxin on contraction of blood vessel smooth muscle. Honda studied structure and function of V. parahaemolyticus thermostable direct hemolysin (TDH). He isolated a mutant producing a TDH-related molecule which did non show hemolytic actibity and found that glycine residue at 90th was replaced with asparagine in the mutant hemolysin. Mizuguchi isolated a transformant which had gene encoding a hemolysin (delta-VPH) of V. parahaemolyticus. Delta-VPH was not produced by usual cultivation of V. parahaemolyticus. However, challenge of delta-VPH preparation to animal model suggested that the toxin was one of the pathogenic factor of the vibrio. Nakazawa found a new hemolysin of Pseudomonas cepatia The hemolysin was noon-proteinic and showed antimycotic activity. These results presented the important information for general understanding of the mechanism of action of bacterial cytolysins.