Biotechnology Research Center, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
Biosci Biotechnol Biochem. 2021 Mar 24;85(4):874-881. doi: 10.1093/bbb/zbaa114.
In Corynebacterium glutamicum, pyruvate dehydrogenase (PDH) and 2-oxoglutarate dehydrogenase (ODH) form a unique hybrid complex in which CgE1p and CgE1o are associated with the CgE2-CgE3 subcomplex. We analyzed the role of a lysine acetylation site in the peripheral subunit-binding domain of CgE2 in PDH and ODH functions. Acetylation-mimic substitution at Lys391 of CgE2 severely reduced the interaction of CgE2 with CgE1p and CgE3, but not with CgE1o, indicating the critical role of this residue in the assembly of CgE1p and CgE3 into the complex. It also suggested that Lys391 acetylation inhibited the binding of CgE1p and CgE3 to CgE2, thereby affecting PDH and ODH activities. Interestingly, the CgE2-K391R variant strain showed increased l-glutamate production and reduced pyruvate accumulation. Kinetic analysis suggested that the increased affinity of the K391R variant toward pyruvate might be advantageous for l-glutamate production.
在谷氨酸棒杆菌中，丙酮酸脱氢酶（PDH）和 2-酮戊二酸脱氢酶（ODH）形成一个独特的混合复合物，其中 CgE1p 和 CgE1o 与 CgE2-CgE3 亚基复合物相关联。我们分析了 CgE2 外周亚基结合域中赖氨酸乙酰化位点在 PDH 和 ODH 功能中的作用。CgE2 的赖氨酸 391 处的乙酰化模拟取代严重降低了 CgE2 与 CgE1p 和 CgE3 的相互作用，但与 CgE1o 没有相互作用，表明该残基在 CgE1p 和 CgE3 组装到复合物中的关键作用。这也表明赖氨酸 391 的乙酰化抑制了 CgE1p 和 CgE3 与 CgE2 的结合，从而影响 PDH 和 ODH 的活性。有趣的是，CgE2-K391R 变体菌株表现出增加的 l-谷氨酸产量和减少的丙酮酸积累。动力学分析表明，K391R 变体对丙酮酸的亲和力增加可能有利于 l-谷氨酸的生产。
