Accomplice fingered in cholera toxicity

A study published in March 2001 revealed one of the ways that cholera toxin hijacks some of the cell’s own machinery. In uncovering part of the toxin’s trail, a team led by Tom Rapoport, Howard Hughes investigator and Harvard Medical School professor of cell biology, has also identified a novel mechanism for chaperoning the unfolding of proteins, one that may have broader implications for protein transport within cells. The effects of cholera, one of the most rapidly fatal diseases known, are largely due to a toxin secreted by the bacterium Vibrio cholerae that acts on intestinal epithelial cells. The cholera toxin is a deft invader, making its way backwards through the cell’s own pathways for secreting and degrading proteins. Once there, the toxin initiates a signaling cascade that results in chloride channels opening at the cellular membrane, causing the massive loss of water and the diarrhea associated with cholera.