Reversible Protein Acetylation and Chromatin Function

描述（由申请人提供）：该拟议项目的总体目标是了解染色质重塑酶的分子机制及其在控制染色体功能中的作用。关于染色质动力学在调节基因转录和DNA代谢中的作用的新信息的爆炸使得需要理解可逆地修饰染色质的酶的分子和调节机制。具体目标是了解沉默信息调节器2（Sir 2）家族酶在生物化学和细胞水平上的功能。最近的证据表明，这些蛋白质具有独特的酶活性（NAD+依赖性蛋白质脱乙酰化），这是其染色质沉默效应所必需的。Sir 2家族在进化上保守，涉及广泛的生物学活性，包括基因沉默、染色体稳定性和通过热量限制延长寿命。主要研究者的实验室最近发现，Sir 2酶是有效的组蛋白/蛋白质脱乙酰酶，其将蛋白质脱乙酰化与全新代谢物O-乙酰基-ADP-核糖的产生偶联。新的证据表明，O-乙酰基-ADP-核糖的产生可能介导重要的生物学功能。这种代谢物可能是理解Sir 2酶的多种生物学功能的关键。例如，O-乙酰基-ADP-核糖的产生可能将细胞核中的基因沉默与适当的代谢控制联系起来。然而，Sir 2蛋白如何完成该反应的机制以及产生O-乙酰基-ADP-核糖的功能意义尚不清楚。为了探索这种独特的酶家族的生物学和生物化学功能，该提案提供了一种完全集成的方法，利用生物化学，蛋白质组学方法，生物化学基因组学，结构和化学来解决Sir 2酶如何以及为什么催化这种独特的反应和O-乙酰基-ADP-核糖的产生。考虑到与染色体不稳定性和疾病有关的大量数据（例如，癌症）与染色质重塑酶，我们对这些分子机制的理解可能会导致抑制Sir 2酶的合理疗法的发展。

DESCRIPTION (provided by applicant): The overall aim of this proposed project is to understand the molecular mechanisms of chromatin remodeling enzymes and their role in controlling chromosomal functions. An explosion of new information on the role of chromatin dynamics in modulating gene transcription and DNA metabolism has necessitated the need to understand the molecular and regulatory mechanisms for enzymes that reversibly modify chromatin. The specific aims are directed at understanding the function of the Silent Information Regulator 2 (Sir2) family of enzymes, both at the biochemical and cellular level. Recent evidence has indicated that these proteins possess unique enzymatic activities (NAD+-dependent protein deacetylation) that are required for their chromatin silencing effects. Evolutionarily conserved, the Sir2 family has been implicated in a wide range of biological activities, including gene silencing, chromosomal stability and life-span extension via caloric restriction. The principal investigator's laboratory has recently discovered that Sir2 enzymes are potent histone/protein deacetylases that couple protein deacetylation to the production of a completely novel metabolite O-acetyl-ADP-ribose. New evidence suggests that generation of O-acetyl-ADP-ribose may mediate important biological functions. This metabolite may be the key to understanding the diverse biological functions of Sir2 enzymes. For instance, the generation of O-acetyl-ADP-ribose may link gene silencing in the nucleus with proper metabolic control. However, the mechanism of how Sir2 proteins accomplish this reaction and the functional significance of producing O-acetyl-ADP-ribose are not understood. To probe the biological and biochemical functions of this unique family of enzymes, this proposal provides a fully integrated approach utilizing biochemistry, proteomic methods, biochemical genomics, structure and chemistry to address how and why Sir2 enzymes catalyze this unique reaction and the production of O-acetyl-ADP-ribose. Given the vast data relating chromosomal instability and disease (e.g., cancer) with chromatin remodeling enzymes, our understanding of these molecular mechanisms may lead to the development of rationale therapeutics that inhibit Sir2 enzyme.