Many enzymes that catalyze protein post-translational modifications (PTM) can specifically modify multiple target proteins. However, little is known regarding the molecular basis and evolution of multi-specificity in these enzymes. Here, we used a combined bioinformatics and experimental approaches to investigate the evolution of multi-specificity in the sirtuin-1 (SIRT1) deacetylase. Guided by bioinformatics analysis of SIRT1 orthologues 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 orthologues 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 multi-specificity, suggesting that the multi-specificity of some metazoan sirtuins, such as hSIRT1, could be a relatively ancient trait.

中文翻译：

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在自然进化过程中，人类SIRT1的多特异性受到活性位点附近取代的调节。

许多催化蛋白质翻译后修饰（PTM）的酶都可以特异性修饰多个目标蛋白质。然而，关于这些酶的分子基础和多特异性的进化知之甚少。在这里，我们使用了结合的生物信息学和实验方法来研究sirtuin-1（SIRT1）脱乙酰酶的多特异性进化。在对SIRT1直向同源物和底物进行生物信息学分析的指导下，我们鉴定并检查了后生动物和真菌中沉默调节蛋白进化过程中发生的重要氨基酸取代。我们发现，基于来自真菌的沉默调节蛋白直向同源物，在这些位置上人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（仅存在于后生动物中）的活性降低，而不影响对保守的组蛋白底物的高活性。祖先序列重建的结果与祖先sirtuin蛋白表现出多特异性的模型一致，这表明某些后生代sirtuin的多特异性，例如hSIRT1，可能是一个相对古老的特征。