Van Damme Petra, Kalvik Thomas V, Starheim Kristian K, Jonckheere Veronique, Myklebust Line M, Menschaert Gerben, Varhaug Jan Erik, Gevaert Kris, Arnesen Thomas
From the ‡Medical Biotechnology Center, VIB, B-9000 Ghent, Belgium;
§Department of Biochemistry, Ghent University, B-9000 Ghent, Belgium.
Mol Cell Proteomics. 2016 Nov;15(11):3361-3372. doi: 10.1074/mcp.M116.061010. Epub 2016 Sep 30.
N-terminal acetylation (Nt-acetylation) by N-terminal acetyltransferases (NATs) is one of the most common protein modifications in eukaryotes. The NatC complex represents one of three major NATs of which the substrate profile remains largely unexplored. Here, we defined the in vivo human NatC Nt-acetylome on a proteome-wide scale by combining knockdown of its catalytic subunit Naa30 with positional proteomics. We identified 46 human NatC substrates, expanding our current knowledge on the substrate repertoire of NatC which now includes proteins harboring Met-Leu, Met-Ile, Met-Phe, Met-Trp, Met-Val, Met-Met, Met-His and Met-Lys N termini. Upon Naa30 depletion the expression levels of several organellar proteins were found reduced, in particular mitochondrial proteins, some of which were found to be NatC substrates. Interestingly, knockdown of Naa30 induced the loss of mitochondrial membrane potential and fragmentation of mitochondria. In conclusion, NatC Nt-acetylates a large variety of proteins and is essential for mitochondrial integrity and function.
由N端乙酰基转移酶（NATs）进行的N端乙酰化（Nt-乙酰化）是真核生物中最常见的蛋白质修饰之一。NatC复合物是三种主要的NATs之一，其底物谱在很大程度上仍未被探索。在这里，我们通过将其催化亚基Naa30的敲低与定位蛋白质组学相结合，在全蛋白质组范围内定义了体内人类NatC N端乙酰化组。我们鉴定出46种人类NatC底物，扩展了我们目前对NatC底物库的认识，现在该底物库包括具有甲硫氨酸-亮氨酸、甲硫氨酸-异亮氨酸、甲硫氨酸-苯丙氨酸、甲硫氨酸-色氨酸、甲硫氨酸-缬氨酸、甲硫氨酸-甲硫氨酸、甲硫氨酸-组氨酸和甲硫氨酸-赖氨酸N端的蛋白质。在Naa30缺失后，发现几种细胞器蛋白的表达水平降低，特别是线粒体蛋白，其中一些被发现是NatC底物。有趣的是，Naa30的敲低导致线粒体膜电位丧失和线粒体碎片化。总之，NatC对多种蛋白质进行N端乙酰化，对线粒体的完整性和功能至关重要。
