Bacterial pyruvate oxidation, anaplerosis, and PEP interconversion

A reusable bacterial central-carbon module centered on three direct fates of pyruvate and phosphoenolpyruvate: oxidative conversion of pyruvate to acetyl-CoA by the pyruvate dehydrogenase complex, replenishment of oxaloacetate by pyruvate carboxylase or phosphoenolpyruvate carboxylase, and direct interconversion between phosphoenolpyruvate and pyruvate. The module excludes complete glycolysis, the tricarboxylic acid cycle, lactate and acetate utilization, amino-acid degradation, methylglyoxal detoxification, fatty-acid synthesis, and other reactions included on broad pathway maps.

The module is intentionally narrower than a KEGG pyruvate-metabolism map. Cofactor installation, upstream pyruvate production by complete glycolytic or Entner-Doudoroff routes, downstream acetyl-CoA and oxaloacetate utilization, and substrate-specific routes that merely produce or consume pyruvate are cross-module dependencies. An organism may realize one or more anaplerotic routes and one or both direct PEP/pyruvate directions. The pyruvate dehydrogenase branch is optional because bacteria may instead oxidize pyruvate through enzymes such as pyruvate:ferredoxin oxidoreductase, particularly under anaerobic conditions.