Støve Svein Isungset, Magin Robert S, Foyn Håvard, Haug Bengt Erik, Marmorstein Ronen, Arnesen Thomas
Department of Molecular Biology, University of Bergen, 5020 Bergen, Norway; Department of Surgery, Haukeland University Hospital, 5021 Bergen, Norway.
Department of Biochemistry and Biophysics, Abramson Family Cancer Research Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Graduate Group in Biochemistry and Molecular Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Program in Gene Expression and Regulation, Wistar Institute, Philadelphia, PA 19104, USA.
Structure. 2016 Jul 6;24(7):1044-56. doi: 10.1016/j.str.2016.04.020. Epub 2016 Jun 16.
N-Terminal acetylation is a common and important protein modification catalyzed by N-terminal acetyltransferases (NATs). Six human NATs (NatA-NatF) contain one catalytic subunit each, Naa10 to Naa60, respectively. In contrast to the ribosome-associated NatA to NatE, NatF/Naa60 specifically associates with Golgi membranes and acetylates transmembrane proteins. To gain insight into the molecular basis for the function of Naa60, we developed an Naa60 bisubstrate CoA-peptide conjugate inhibitor, determined its X-ray structure when bound to CoA and inhibitor, and carried out biochemical experiments. We show that Naa60 adapts an overall fold similar to that of the catalytic subunits of ribosome-associated NATs, but with the addition of two novel elongated loops that play important roles in substrate-specific binding. One of these loops mediates a dimer to monomer transition upon substrate-specific binding. Naa60 employs a catalytic mechanism most similar to Naa50. Collectively, these data reveal the molecular basis for Naa60-specific acetyltransferase activity with implications for its Golgi-specific functions.
N 端乙酰化是一种由 N 端乙酰转移酶（NATs）催化的常见且重要的蛋白质修饰。六种人类 NATs（NatA - NatF）分别包含一个催化亚基，即 Naa10 至 Naa60。与核糖体相关的 NatA 至 NatE 不同，NatF/Naa60 特异性地与高尔基体膜结合并乙酰化跨膜蛋白。为深入了解 Naa60 功能的分子基础，我们开发了一种 Naa60 双底物辅酶 A - 肽共轭抑制剂，确定了其与辅酶 A 和抑制剂结合时的 X 射线结构，并进行了生化实验。我们发现，Naa60 具有与核糖体相关 NATs 的催化亚基相似的整体折叠结构，但增加了两个在底物特异性结合中起重要作用的新型延伸环。其中一个环在底物特异性结合时介导二聚体向单体的转变。Naa60 采用的催化机制与 Naa50 最为相似。这些数据共同揭示了 Naa60 特异性乙酰转移酶活性的分子基础，对其高尔基体特异性功能具有重要意义。
