Molecular and Environmental Biology Centre, Department of Biology, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
Gene Therapy and Regulation of Gene Expression Program, Centro de Investigación Médica Aplicada, Universidad de Navarra, Avda Pio XII 55, Pamplona 31008, Spain.
Int J Biochem Cell Biol. 2018 Feb;95:35-42. doi: 10.1016/j.biocel.2017.12.004. Epub 2017 Dec 9.
The pro-apoptotic Bax protein is the main effector of mitochondrial permeabilization during apoptosis. Bax is controlled at several levels, including post-translational modifications such as phosphorylation and S-palmitoylation. However, little is known about the contribution of other protein modifications to Bax activity. Here, we used heterologous expression of human Bax in yeast to study the involvement of N-terminal acetylation by yNaa20p (yNatB) on Bax function. We found that human Bax is N-terminal (Nt-)acetylated by yNaa20p and that Nt-acetylation of Bax is essential to maintain Bax in an inactive conformation in the cytosol of yeast and Mouse Embryonic Fibroblast (MEF) cells. Bax accumulates in the mitochondria of yeast naa20Δ and Naa25 MEF cells, but does not promote cytochrome c release, suggesting that an additional step is required for full activation of Bax. Altogether, our results show that Bax N-terminal acetylation by NatB is involved in its mitochondrial targeting.
促凋亡 Bax 蛋白是细胞凋亡过程中线粒体通透化的主要效应因子。Bax 的活性受到多种水平的调控，包括翻译后修饰，如磷酸化和 S-棕榈酰化。然而，人们对其他蛋白修饰对 Bax 活性的贡献知之甚少。在这里，我们利用酵母中异源表达人源 Bax 来研究 N 端乙酰化酶 yNaa20p（yNatB）对 Bax 功能的影响。我们发现人源 Bax 可被 yNaa20p 进行 N 端乙酰化，并且 Bax 的 N 端乙酰化对于 Bax 在酵母和小鼠胚胎成纤维细胞（MEF）细胞胞质中的无活性构象的维持是必需的。 Bax 在酵母 naa20Δ 和 Naa25 MEF 细胞中积累在线粒体中，但不能促进细胞色素 c 的释放，这表明 Bax 的完全激活还需要额外的步骤。总的来说，我们的结果表明 NatB 介导的 Bax N 端乙酰化参与了 Bax 的线粒体靶向。
