Pyruvate Is Synthesized by Two Pathways in Pea Bacteroids with Different Efficiencies for Nitrogen Fixation

Nitrogen fixation in legume bacteroids is energized by the metabolism of dicarboxylic acids, which requires their oxidation to both oxaloacetate and pyruvate. In alfalfa bacteroids, production of pyruvate requires NAD+ malic enzyme (Dme) but not NADP+ malic enzyme (Tme). However, we show that Rhizobium leguminosarum has two pathways for pyruvate formation from dicarboxylates catalyzed by Dme and by the combined activities of phosphoenolpyruvate …