Department of Life Sciences, Ben-Gurion University of the Negev, Be'er Sheva, 84105, Israel.
Smartzyme Innovation LTD, Ilan Ramon, Science Park-Ness Ziona, Ness Ziona, Israel.
Sci Rep. 2018 Feb 23;8(1):3538. doi: 10.1038/s41598-018-21887-9.
Mammalian SIRT6 is a well-studied histone deacetylase that was recently shown to exhibit high protein deacylation activity enabling the removal of long chain fatty acyl groups from proteins. SIRT6 was shown to play key roles in cellular homeostasis by regulating a variety of cellular processes including DNA repair and glucose metabolism. However, the link between SIRT6 enzymatic activities and its cellular functions is not clear. Here, we utilized a directed enzyme evolution approach to generate SIRT6 mutants with improved deacylation activity. We found that while two mutants show increased deacylation activity at high substrate concentration and improved glucose metabolism they exhibit no improvement and even abolished deacetylation activity on H3K9Ac and H3K56Ac in cells. Our results demonstrate the separation of function between SIRT6 catalytic activities and suggest that SIRT6 deacylation activity in cells is important for glucose metabolism and can be mediated by still unknown acylated cellular proteins.
哺乳动物 SIRT6 是一种研究得很好的组蛋白去乙酰化酶，最近的研究表明它具有很高的蛋白质去酰基化活性，能够从蛋白质上去除长链脂肪酸基团。SIRT6 通过调节多种细胞过程，包括 DNA 修复和葡萄糖代谢，在细胞内稳态中发挥关键作用。然而，SIRT6 酶活性与其细胞功能之间的联系尚不清楚。在这里，我们利用定向酶进化方法生成了具有改进去酰基化活性的 SIRT6 突变体。我们发现，虽然两个突变体在高底物浓度下显示出增强的去酰基化活性和改善的葡萄糖代谢，但它们在细胞中对 H3K9Ac 和 H3K56Ac 的去乙酰化活性没有改善，甚至被废除。我们的结果表明 SIRT6 催化活性的功能分离，并表明 SIRT6 在细胞中的去酰基化活性对葡萄糖代谢很重要，并可由仍未知的酰化细胞蛋白介导。
