A (PEP)py Response

摘要

Phosphoenolpyruvate (PEP), the final intermediate of glycolysis, is a central cellular metabolite. Besides its conversion to pyruvate by pyruvate kinase during glycolysis, in prokaryotes it is also the substrate for glucose phosphorylation (required for the import of glucose), and in some bacteria it is also converted to oxaloacetate by PEP carboxylase—an anapleurotic reaction that replenishes an intermediate in the tricarbox-ylic acid (TCA) cycle. Xu et at. found that as expected, depriving Escherichia coli of glucose resulted in a decrease in early glycolysis intermediates such as fructose-l,6,-biphosphate (FBP), but also observed the remarkable finding seen by others, that PEP increased at least 10-fold. A metabolic flux analysis showed that this was likely due to almost complete inhibition of PEP carboxylase.