VapB

VapB is a bacterial toxin produced by certain strains of Vibrio cholerae, a bacterium responsible for causing cholera, a severe diarrheal disease. VapB is a component of the cholera toxin complex, which is a protein complex that plays a crucial role in the pathogenesis of cholera. The cholera toxin complex is composed of two subunits: the B subunit, which is responsible for binding to the cell surface, and the A subunit, which is responsible for the toxic activity.

VapB is a 28-kDa protein that is encoded by the ctxB gene. It is a member of the ADP-ribosylating toxins, which modify cellular proteins by adding ADP-ribose groups. VapB is responsible for the ADP-ribosylation of the Gs alpha subunit of the G protein, which leads to the activation of adenylate cyclase and the subsequent increase in cyclic AMP levels. This increase in cyclic AMP levels results in the activation of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel, leading to the secretion of chloride ions and the dehydration of the intestinal lumen, which is a key feature of cholera.

VapB is a potent toxin and is responsible for the majority of the symptoms of cholera. It is also a target for the development of vaccines and therapeutic agents. The development of a vaccine against VapB has been a major focus of research in the field of cholera vaccine development. The VapB subunit is also a target for the development of monoclonal antibodies and other therapeutic agents that can neutralize the toxin and prevent the development of cholera.