Final answer:
The CFTR chloride channel during a Vibrio cholera infection opens due to adenylyl cyclase-mediated phosphorylation, leading to severe fluid loss and diarrhea.
Step-by-step explanation:
The opening of the CFTR chloride channel during a Vibrio cholera infection is caused by continued phosphorylation by adenylyl cyclase.
Cholera is caused by the bacterium Vibrio cholerae, which releases a toxin that binds to intestinal cells and modifies a G-protein controlling the opening of the chloride channel. This modification by the cholera toxin results in the activation of adenylyl cyclase, leading to increased levels of cAMP, which in turn keeps the CFTR channel continuously open. This mechanism is responsible for the excessive loss of fluids into the intestinal lumen, causing severe diarrhea and potentially fatal dehydration.