Maturation Pathway of Hemolysin of Aeromonas sobria and the Mechanism of Action of the Hemolysin

Abstract

Aeromonas sobria has been recognized as pathogens associated with acute gastroenteritis in both adults and children. The major virulence factor has been proposed to be hemolysin which possesses both hemolytic and enterotoxic activities. Mature (bio-active) hemolysin secreted out of cells binds to the target cells of the host and injure the cells. However, hemolysin remained in bacteria can not express such toxicity. It means that the maturation and secretion pathway of hemolysin is closely related to the pathogenicity of bacteria. Therefore, I examined the pathway and clarified the following events. Hemolysin synthesized in cytoplasm translocates across the inner membrane and appears in a periplasmic space. Hemolysins appeared in the space associates to form dimer in the space. The C-terminal region of hemolysin functions as a trigger in the association. Dimerized hemolysin crosses the outer membrane and emerges in milieu, but monomer can not cross it. Therefore, the C-terminal region of hemolysin attributes not only to the formation of the dimer but also to its secretion into milieu. Hemolysin emerged in milieu is inactive. Inactive hemolysin is converted to bio-Active hemolysin by deleting its carboxyl-terminal 42-amino-acid peptide. Active hemolysin generated binds to the receptor of the target cell and stimulates the production of cyclic AMP by the cell. I assume that this stimulation closely relates to the induction of diarrhea by hemolysin.