Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Canada.
J Proteomics. 2013 Apr 9;81:80-90. doi: 10.1016/j.jprot.2012.09.026. Epub 2012 Oct 2.
Rtt109 is a fungal-specific histone acetyltransferase (HAT) that associates with either Vps75 or Asf1 to acetylate histone H3. Recent biochemical and structural studies suggest that site-specific acetylation of H3 by Rtt109 is dictated by the binding chaperone where Rtt109-Asf1 acetylates K56, while Rtt109-Vps75 acetylates K9 and K27. To gain further insights into the roles of Vps75 and Asf1 in directing site-specific acetylation of H3, we used quantitative proteomics to profile the global and site-specific changes in H3 and H4 during in vitro acetylation assays with Rtt109 and its chaperones. Our analyses showed that Rtt109-Vps75 preferentially acetylates H3 K9 and K23, the former residue being the major acetylation site. At high enzyme-to-substrate ratio, Rtt109 also acetylated K14, K18, K27 and to a lower extent K56 of histone H3. Importantly, this study revealed that in contrast to Rtt109-Vps75, Rtt109-Asf1 displayed a far greater site-specificity, with K56 being the primary site of acetylation. For the first time, we also report the acetylation of histone H4 K12 by Rtt109-Vps75, whereas Rtt109-Asf1 showed no detectable activity toward H4. This article is part of a Special Issue entitled: From protein structures to clinical applications.
Rtt109 是一种真菌特异性组蛋白乙酰转移酶（HAT），可与 Vps75 或 Asf1 结合，乙酰化组蛋白 H3。最近的生化和结构研究表明，Rtt109 对 H3 的特异性位点乙酰化是由结合伴侣决定的，其中 Rtt109-Asf1 乙酰化 K56，而 Rtt109-Vps75 乙酰化 K9 和 K27。为了更深入地了解 Vps75 和 Asf1 在指导 H3 特异性乙酰化中的作用，我们使用定量蛋白质组学方法在体外乙酰化测定中分析了 Rtt109 及其伴侣与 H3 和 H4 的全局和特异性变化。我们的分析表明，Rtt109-Vps75 优先乙酰化 H3 K9 和 K23，前者是主要的乙酰化位点。在高酶与底物的比例下，Rtt109 还乙酰化 H3 的 K14、K18、K27，以及 K56 的程度较低。重要的是，这项研究表明，与 Rtt109-Vps75 相反，Rtt109-Asf1 表现出更高的特异性，K56 是主要的乙酰化位点。我们首次报道了 Rtt109-Vps75 对组蛋白 H4 K12 的乙酰化作用，而 Rtt109-Asf1 对 H4 没有检测到乙酰化活性。本文是一个特刊的一部分，题为：从蛋白质结构到临床应用。
