Department of Chemistry, University of Pennsylvania, Philadelphia, United States.
Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States.
Elife. 2020 Sep 4;9:e57491. doi: 10.7554/eLife.57491.
NatB is one of three major N-terminal acetyltransferase (NAT) complexes (NatA-NatC), which co-translationally acetylate the N-termini of eukaryotic proteins. Its substrates account for about 21% of the human proteome, including well known proteins such as actin, tropomyosin, CDK2, and α-synuclein (αSyn). Human NatB (hNatB) mediated N-terminal acetylation of αSyn has been demonstrated to play key roles in the pathogenesis of Parkinson's disease and as a potential therapeutic target for hepatocellular carcinoma. Here we report the cryo-EM structure of hNatB bound to a CoA-αSyn conjugate, together with structure-guided analysis of mutational effects on catalysis. This analysis reveals functionally important differences with human NatA and NatB, resolves key hNatB protein determinants for αSyn N-terminal acetylation, and identifies important residues for substrate-specific recognition and acetylation by NatB enzymes. These studies have implications for developing small molecule NatB probes and for understanding the mode of substrate selection by NAT enzymes.
NatB 是三种主要的 N 端乙酰转移酶（NAT）复合物（NatA-NatC）之一，它在翻译过程中乙酰化真核蛋白的 N 端。其底物约占人类蛋白质组的 21%，包括众所周知的蛋白质，如肌动蛋白、原肌球蛋白、CDK2 和 α-突触核蛋白（αSyn）。已证明人类 NatB（hNatB）介导的 αSyn 的 N 端乙酰化在帕金森病的发病机制中起关键作用，并且是肝细胞癌的潜在治疗靶标。在这里，我们报告了与 CoA-αSyn 缀合物结合的 hNatB 的冷冻电镜结构，以及对催化突变效应的结构导向分析。该分析揭示了与人类 NatA 和 NatB 的功能重要差异，解析了 hNatB 蛋白对 αSyn N 端乙酰化的关键决定因素，并确定了 NatB 酶对底物特异性识别和乙酰化的重要残基。这些研究对于开发小分子 NatB 探针以及理解 NAT 酶的底物选择模式具有重要意义。
