Rhabdomyolysin

Rhabdomyolysin is a protein toxin produced by the bacterium Vibrio cholerae. It is also known as cholera toxin subunit B, or CTB. This toxin plays a crucial role in the pathogenesis of cholera, a severe diarrheal disease. Rhabdomyolysin is composed of two subunits: subunit A and subunit B. Subunit B is responsible for binding the toxin to specific receptors on the surface of intestinal cells, specifically GM1 gangliosides. This binding is essential for the entry of subunit A into the cell. Once inside, subunit A activates an enzyme called adenylyl cyclase, which leads to an overproduction of cyclic adenosine monophosphate (cAMP). The elevated levels of cAMP disrupt the normal balance of ions and water in the intestinal cells, causing a massive efflux of water into the intestinal lumen. This results in the characteristic profuse, watery diarrhea of cholera. While rhabdomyolysin itself is not directly cytotoxic, its ability to initiate this cascade of events makes it a potent virulence factor. Research into rhabdomyolysin has also led to the development of vaccines and diagnostic tools for cholera.