Structural Basis of HDAC Substrate Specificity and Inhibition

项目摘要/摘要 可逆组蛋白赖氨酸乙酰化是一种基本的翻译后修饰 和非组蛋白。赖氨酸乙酰化可以改变蛋白质-蛋白质和蛋白质-DNA相互作用，蛋白质 稳定性和酶的激活/失活。组蛋白是赖氨酸乙酰化的主要调节因子之一。 脱乙酰酶(HDAC)家族。在已知的18个人类HDAC中，有11个是金属依赖的水解酶，与 乙酰多胺酰胺水解酶(APAHs)。HDAC对基因表达的调控起着重要作用 以及许多其他关键的细胞过程。值得注意的是，在多个人类中观察到异常的赖氨酸乙酰化。 疾病，包括癌症；因此，HDAC是一个有效的药物靶点。尽管它们具有重要的生物学功能 和作为药物靶点的临床作用，对HDAC底物特异性和 抑制力。HDAC 10和11尤其如此，它们最不能很好地描述 金属依赖型HDAC。 我们的初步研究和系统发育比较表明，HDAC 10和11可能 作为双乙酰赖氨酸和乙酰多胺脱乙酰酶，具有独特的底物结合部位 建筑。然而，HDAC10和11如何适应小的多胺底物以及大的 含有女性乙酰赖氨酸部分的蛋白质底物尚不清楚。此外，虽然经典的HDAC抑制剂 如SAHA等已知能抑制HDAC 10和11，这种抑制的分子基础未知为NO HDAC10-抑制剂或HDAC11-抑制物复合结构可供选择。事实上，HDAC11的任何结构都不是 尽管由于其有限的序列同一性，HDAC11代表了唯一的一类HDAC 与其他HDAC一起工作。我们建议研究HDAC 10和11的结构-功能关系，以建立 了解底物识别、催化和抑制的分子基础。由于缺乏 结构和机械研究侧重于HDAC 10和11，我们目前没有装备来设计 HDAC同工酶特异性抑制剂。 我建议通过(1)来研究HDAC底物识别和抑制的分子机制。 探讨HDAC10底物专一性的结构基础；(2)确定 HDAC10抑制；以及(3)确定HDAC11的结构-功能关系。如上所述 上图中，异常的赖氨酸乙酰化是某些癌症和其他人类疾病的标志；因此 HDAC是关键的药物靶标。目前，FDA批准了四种广特异性HDAC抑制剂用于癌症 化疗，但同工酶特异性的HDAC抑制剂大多不可用。我们的研究旨在更好地 了解特性不佳的HDAC的结构和功能，以促进设计 用于治疗人类疾病，特别是癌症的特定HDAC抑制剂。

Project Summary/Abstract Reversible protein lysine acetylation is a fundamental posttranslational modification observed in histone and non-histone proteins. Lysine acetylation can alter protein-protein and protein-DNA interactions, protein stability, and enzyme activation/deactivation. Among the major regulators of lysine acetylation is the histone deacetylase (HDAC) family. Of the 18 known human HDACs, 11 are metal-dependent hydrolases related to the acetylpolyamine amidohydrolases (APAHs). The HDACs contribute to the regulation of gene expression and many other critical cellular processes. Notably, abnormal lysine acetylation is observed in multiple human disorders, including cancer; thus HDACs are a validated drug target. Despite their critical biological functions and clinical roles as drug targets, little is known about the molecular basis for HDAC substrate specificity and inhibition. This is particularly the case for HDACs 10 and 11, which are the least well characterized of the metal-dependent HDACs. Our preliminary studies coupled with phylogenetic comparisons suggest that HDACs 10 and 11 may function as dual acetyllysine and acetylpolyamine deacetylases with unique substrate binding site architectures. However, how HDAC10 and 11 could accommodate small polyamine substrates as well as large protein substrates containing sissile acetyllysine moieties is unclear. In addition, while classic HDAC inhibitors such as SAHA are known to inhibit HDACs 10 and 11, the molecular basis for this inhibition is unknown as no HDAC10-inhibitor or HDAC11-inibitor complex structures are available. In fact, no structure of HDAC11 is available, despite the fact that HDAC11 represents a unique class of HDAC due to its limited sequence identity with other HDACs. We propose to study structure-function relationships for HDACs 10 and 11 to establish a molecular foundation for understanding substrate recognition, catalysis, and inhibition. Due to a lack of structural and mechanistic studies focusing on HDACs 10 and 11, we are currently unequipped to design HDAC isozyme-specific inhibitors. I propose to study the molecular mechanisms of HDAC substrate recognition and inhibition by (1) exploring the structural basis of HDAC10 substrate specificity; (2) defining the structural basis of HDAC10 inhibition; and (3) determining structure-function relationships for HDAC11. As mentioned above, aberrant lysine acetylation is a hallmark of certain cancers and other human disorders; therefore HDACs are critical drug targets. Currently, four broad-specificity HDAC inhibitors are FDA-approved for cancer chemotherapy, but isozyme-specific HDAC inhibitors are mostly unavailable. Our studies aim to better understand the structure and function of poorly characterized HDACs with the goal of facilitating the design of specific HDAC inhibitors for use in human disorders, particularly cancer.