Final answer:
The enzyme whose inhibition is associated with the fall of cyclic-AMP (cAMP) levels upon glucose transport into a bacterial cell is adenylate cyclase. This inhibition is part of a regulatory mechanism that controls the use of alternative sugars when glucose is available, known as catabolite repression.
Step-by-step explanation:
The transport of glucose into a bacterial cell causes the intracellular level of cyclic-AMP (cAMP) to fall because the enzyme adenylate cyclase is inhibited. When glucose is abundant, cAMP levels decrease, reducing the activity of cAMP-dependent pathways such as those involved in the utilization of alternative sugars like lactose.
This process of regulation is known as catabolite repression, which occurs through a mechanism referred to as inducer exclusion. High levels of glucose lead to the dephosphorylation of enzyme IIA (EIIA), a component of the phosphoenolpyruvate:sugar phosphotransferase system. The unphosphorylated form of EIIA inhibits adenylate cyclase, therefore reducing cAMP synthesis.
Glucose transport into the cell affects levels of cAMP by altering the phosphorylation state of EIIA, which effectively controls the activity of adenylate cyclase and subsequently influences the cellular response to glucose availability.