Design, Synthesis, and Evaluation of Polyamine Deacetylase Inhibitors, and High-Resolution Crystal Structures of Their Complexes with Acetylpolyamine Amidohydrolase
作者:Christophe Decroos、David W. Christianson
DOI:10.1021/acs.biochem.5b00536
日期:2015.8.4
Polyamines are essential aliphatic polycations that bind to nucleic acids and accordingly are involved in a variety of cellular processes. Polyamine function can be regulated by acetylation and deacetylation, just as histone function can be regulated by lysine acetylation and deacetylation. Acetylpolyamine amidohydrolase (APAH) from Mycoplana ramosa is a zinc-dependent polyamine deacetylase that shares approximately 20% amino acid sequence identity with human histone deacetylases. We now report the X-ray crystal structures of APAH–inhibitor complexes in a new and superior crystal form that diffracts to very high resolution (1.1–1.4 Å). Inhibitors include previously synthesized analogues of N8-acetylspermidine bearing trifluoromethylketone, thiol, and hydroxamate zinc-binding groups [Decroos, C., Bowman, C. M., and Christianson, D. W. (2013) Bioorg. Med. Chem. 21, 4530], and newly synthesized hydroxamate analogues of shorter, monoacetylated diamines, the most potent of which is the hydroxamate analogue of N-acetylcadaverine (IC50 = 68 nM). The high-resolution crystal structures of APAH–inhibitor complexes provide key inferences about the inhibition and catalytic mechanism of zinc-dependent deacetylases. For example, the trifluoromethylketone analogue of N8-acetylspermidine binds as a tetrahedral gem-diol that mimics the tetrahedral intermediate and its flanking transition states in catalysis. Surprisingly, this compound is also a potent inhibitor of human histone deacetylase 8 with an IC50 of 260 nM. Crystal structures of APAH–inhibitor complexes are determined at the highest resolution of any currently existing zinc deacetylase structure and thus represent the most accurate reference points for understanding structure–mechanism and structure–inhibition relationships in this critically important enzyme family.
多胺是必需的脂肪族多阳离子,能与核酸结合,因此参与多种细胞过程。多胺的功能可以通过乙酰化和去乙酰化进行调控,正如组蛋白的功能也可以通过赖氨酸的乙酰化和去乙酰化进行调控。来自Mycoplana ramosa的乙酰多胺酰胺水解酶(APAH)是一种锌依赖性多胺去乙酰化酶,其氨基酸序列与人类组蛋白去乙酰化酶约有20%的相似性。我们现报告APAH–抑制剂复合物的X射线晶体结构,采用了一种新的且更优的晶体形态,能够达到非常高的分辨率(1.1–1.4 Å)。抑制剂包括之前合成的N8-乙酰斯表明胺的类似物,这些类似物带有三氟甲基酮、硫醇和羟肟酸锌结合基团【Decroos, C., Bowman, C. M., 和 Christianson, D. W. (2013) Bioorg. Med. Chem. 21, 4530】以及新合成的短链单乙酰化二胺的羟肟酸类似物,其中最强效的是N-乙酰尸胺的羟肟酸类似物(IC50 = 68 nM)。APAH–抑制剂复合物的高分辨率晶体结构提供了关于锌依赖性去乙酰化酶的抑制和催化机制的关键推论。例如,N8-乙酰斯表明胺的三氟甲基酮类似物以四面体gem-diol的形式结合,模拟催化中的四面体中间体及其相邻的过渡态。令人惊讶的是,这种化合物也是人类组蛋白去乙酰化酶8的强效抑制剂,其IC50为260 nM。APAH–抑制剂复合物的晶体结构是在现存的锌去乙酰化酶结构中分辨率最高的,因此代表了理解这一关键酶家族中的结构–机制和结构–抑制关系的最准确参考点。