Department of Life Sciences, Ben-Gurion University of the Negev, Be'er Sheva, Israel.
National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Be'er Sheva, Israel.
Mol Biol Evol. 2021 Jan 23;38(2):545-556. doi: 10.1093/molbev/msaa244.
Many enzymes that catalyze protein post-translational modifications can specifically modify multiple target proteins. However, little is known regarding the molecular basis and evolution of multispecificity in these enzymes. Here, we used a combined bioinformatics and experimental approaches to investigate the evolution of multispecificity in the sirtuin-1 (SIRT1) deacetylase. Guided by bioinformatics analysis of SIRT1 orthologs and substrates, we identified and examined important amino acid substitutions that have occurred during the evolution of sirtuins in Metazoa and Fungi. We found that mutation of human SIRT1 at these positions, based on sirtuin orthologs from Fungi, could alter its substrate specificity. These substitutions lead to reduced activity toward K382 acetylated p53 protein, which is only present in Metazoa, without affecting the high activity toward the conserved histone substrates. Results from ancestral sequence reconstruction are consistent with a model in which ancestral sirtuin proteins exhibited multispecificity, suggesting that the multispecificity of some metazoan sirtuins, such as hSIRT1, could be a relatively ancient trait.
许多催化蛋白质翻译后修饰的酶可以特异性地修饰多个靶蛋白。然而，对于这些酶的多特异性的分子基础和进化知之甚少。在这里，我们使用了组合生物信息学和实验方法来研究 sirtuin-1（SIRT1）去乙酰化酶的多特异性进化。通过对 SIRT1 同源物和底物的生物信息学分析，我们鉴定并研究了在后生动物和真菌中 sirtuins 进化过程中发生的重要氨基酸取代。我们发现，基于真菌的 sirtuin 同源物，在这些位置对人 SIRT1 的突变可能会改变其底物特异性。这些取代导致对 K382 乙酰化 p53 蛋白的活性降低，而 K382 乙酰化 p53 蛋白仅存在于后生动物中，而不影响对保守组蛋白底物的高活性。来自祖先序列重建的结果与一个模型一致，该模型表明，祖先 sirtuin 蛋白表现出多特异性，这表明一些后生动物 sirtuins（如 hSIRT1）的多特异性可能是一个相对古老的特征。
