Cholera kills more than 100,000 people yearly and results from consuming food or water contaminated with Vibrio cholerae. The bacterium only expresses virulence factors, proteins that cause disease, when it infects people. Weber et al. investigated how this occurs at a molecular level and discovered that the bacteria possess an “RNA thermometer,” which turns on expression of these virulence factors. At low temperatures, as found in water inhabited by the bacteria, a sequence from the bacterium’s toxT messenger RNA (toxT encodes a protein that turns on virulence gene expression) folds into a structure that prevents its translation. However, at human body temperature, the structure opens up and the bacterium can express its virulence factor genes.
