Department of Life Sciences, National Chung Hsing University, Taichung, 402, Taiwan ROC.
Ph.D. Program in Tissue Engineering and Regenerative Medicine, National Chung Hsing University, Taichung, 402, Taiwan ROC.
Commun Biol. 2023 May 22;6(1):548. doi: 10.1038/s42003-023-04930-y.
Human mitochondrial NAD(P)-dependent malic enzyme (ME2) is well-known for its role in cell metabolism, which may be involved in cancer or epilepsy. We present potent ME2 inhibitors based on cyro-EM structures that target ME2 enzyme activity. Two structures of ME2-inhibitor complexes demonstrate that 5,5'-Methylenedisalicylic acid (MDSA) and embonic acid (EA) bind allosterically to ME2's fumarate-binding site. Mutagenesis studies demonstrate that Asn35 and the Gln64-Tyr562 network are required for both inhibitors' binding. ME2 overexpression increases pyruvate and NADH production while decreasing the cell's NAD/NADH ratio; however, ME2 knockdown has the opposite effect. MDSA and EA inhibit pyruvate synthesis and thus increase the NAD/NADH ratio, implying that these two inhibitors interfere with metabolic changes by inhibiting cellular ME2 activity. ME2 silence or inhibiting ME2 activity with MDSA or EA decreases cellular respiration and ATP synthesis. Our findings suggest that ME2 is crucial for mitochondrial pyruvate and energy metabolism, as well as cellular respiration, and that ME2 inhibitors could be useful in the treatment of cancer or other diseases that involve these processes.
人线粒体 NAD(P)-依赖性苹果酸酶（ME2）以其在细胞代谢中的作用而闻名，它可能与癌症或癫痫有关。我们基于冷冻电镜结构呈现了强效的 ME2 抑制剂，这些抑制剂针对 ME2 酶的活性。两种 ME2-抑制剂复合物的结构表明，5,5'-亚甲基二水杨酸（MDSA）和安布酸（EA）通过别构方式结合到 ME2 的富马酸结合位点。突变研究表明，Asn35 和 Gln64-Tyr562 网络对于两种抑制剂的结合都是必需的。ME2 的过表达会增加丙酮酸和 NADH 的产生，同时降低细胞的 NAD/NADH 比值；然而，ME2 的敲低则会产生相反的效果。MDSA 和 EA 抑制丙酮酸的合成，从而增加 NAD/NADH 比值，这表明这两种抑制剂通过抑制细胞 ME2 活性来干扰代谢变化。ME2 的沉默或用 MDSA 或 EA 抑制 ME2 活性会降低细胞呼吸和 ATP 的合成。我们的研究结果表明，ME2 对于线粒体丙酮酸和能量代谢以及细胞呼吸至关重要，而 ME2 抑制剂可能在治疗涉及这些过程的癌症或其他疾病方面具有应用价值。
