Question

How do bacteria such as E.coli direct the flux of isocitrate away from the TCA cycle and into the glyoxylate cycle when transferred from glucose-containing nutrient media into media that contains acetate instead of glucose

Answer 1

E. coli bacteria use regulatory mechanisms, including the catabolite activator protein (CAP), to direct the flux of isocitrate away from the TCA cycle and into the glyoxylate cycle when transferred from glucose to acetate media. Through the accumulation of cAMP and the activation of CAP, genes needed for the glyoxylate cycle are turned on, allowing the bacteria to utilize acetate as a carbon source.

Step-by-step explanation:

E. coli bacteria have regulatory mechanisms that direct the flux of isocitrate away from the tricarboxylic acid (TCA) cycle and into the glyoxylate cycle when transferred from glucose-containing media to media with acetate. One major regulatory factor involved in this process is the catabolite activator protein (CAP), which helps control gene expression. When glucose levels drop, cyclic AMP (cAMP) accumulates, which then binds to CAP. This cAMP-CAP complex activates the genes needed for the glyoxylate cycle, diverting isocitrate away from the TCA cycle. As a result, the bacteria can utilize acetate as an alternative carbon source.