Malic enzymes participate in key metabolic processes, the MaeB-like malic enzymes carry a catalytic inactive phosphotransacetylase domain whose function remains elusive. Here we show that acetyl-CoA directly binds and inhibits MaeB-like enzymes with a saturable profile under physiological relevant acetyl-CoA concentrations. A MaeB-like enzyme from the nitrogen-fixing bacterium Azospirillum brasilense, namely AbMaeB1, binds both acetyl-CoA and unesterified CoASH in a way that inhibition of AbMaeB1 by acetyl-CoA is relieved by increasing CoASH concentrations. Hence, AbMaeB1 senses the acetyl-CoA/CoASH ratio. We revisited E. coli MaeB regulation to determine the inhibitory constant for acetyl-CoA. Our data support that the phosphotransacetylase domain of MaeB-like enzymes senses acetyl-CoA to dictate the fate of carbon distribution at the phosphoenol-pyruvate / pyruvate / oxaloacetate metabolic node.

苹果酸酶参与关键的代谢过程，MaeB样苹果酸酶带有催化的失活的磷酸转乙酰酶结构域，其功能仍然难以捉摸。在这里，我们表明，在生理相关的乙酰辅酶A浓度下，乙酰辅酶A直接结合并抑制具有饱和特征的MaeB样酶。来自固氮细菌巴西细螺旋藻的MaeB样酶，即AbMaeB1，与乙酰辅酶A和未酯化的CoASH结合，从而通过增加CoASH浓度来减轻乙酰辅酶A对AbMaeB1的抑制作用。因此，AbMaeB1感测到乙酰辅酶A / CoASH比率。我们重新审视了大肠杆菌通过MaeB调节来确定乙酰辅酶A的抑制常数。我们的数据支持MaeB样酶的磷酸转乙酰酶结构域感测到乙酰辅酶A决定了磷酸烯醇-丙酮酸/丙酮酸/草酰乙酸代谢节点处碳分布的命运。