Department of Chemistry, 231 South 34(th) Street, University of Pennsylvania, Philadelphia, PA 19104, USA; Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
Department of Chemistry, 231 South 34(th) Street, University of Pennsylvania, Philadelphia, PA 19104, USA.
Structure. 2021 Oct 7;29(10):1094-1104.e4. doi: 10.1016/j.str.2021.05.003. Epub 2021 May 20.
Protein N-terminal acetylation is predominantly a ribosome-associated modification, with NatA-E serving as the major enzymes. NatC is the most unusual of these enzymes, containing one Naa30 catalytic subunit and two auxiliary subunits, Naa35 and Naa38; and substrate selectivity profile that overlaps with NatE. Here, we report the cryoelectron microscopy structure of S. pombe NatC with a NatE/C-type bisubstrate analog and inositol hexaphosphate (IP), and associated biochemistry studies. We find that the presence of three subunits is a prerequisite for normal NatC acetylation activity in yeast and that IP binds tightly to NatC to stabilize the complex. We also describe the molecular basis for IP-mediated NatC complex stabilization and the overlapping yet distinct substrate profiles of NatC and NatE.
蛋白质 N 端乙酰化主要是一种核糖体相关的修饰，其中 NatA-E 是主要的酶。NatC 是这些酶中最不寻常的一种，它包含一个 Naa30 催化亚基和两个辅助亚基 Naa35 和 Naa38；其底物选择性与 NatE 重叠。在这里，我们报道了带有 NatE/C 型双底物类似物和肌醇六磷酸（IP）的 S. pombe NatC 的冷冻电子显微镜结构，以及相关的生物化学研究。我们发现，三个亚基的存在是酵母中 NatC 正常乙酰化活性的前提条件，并且 IP 与 NatC 紧密结合以稳定复合物。我们还描述了 IP 介导的 NatC 复合物稳定的分子基础，以及 NatC 和 NatE 重叠但又不同的底物谱。
