Structure and substrate binding properties of cobB, a Sir2 homolog protein deacetylase from Escherichia coli
Structure and substrate binding properties of cobB, a Sir2 homolog protein deacetylase from Escherichia coli
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DOI：
10.1016/j.jmb.2004.01.060
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发表时间：
2004-03-26
影响因子：
5.6
通讯作者：
Marmorstein, R
中科院分区：
文献类型：
--
作者：
Zhao, KH;Chai, XM;Marmorstein, R
Sirtuins是一种NAD（+）依赖的蛋白质脱乙酰酶，从细菌到人类都广泛保守，并且在基因调控、代谢和寿命方面发挥重要作用。cobB是一种细菌沉默调节蛋白，其在活性位点赖氨酸处使乙酰辅酶A合成酶（Acs）脱乙酰以刺激其酶活性。在这里，我们报告的结构cobB绑定到一个乙酰赖氨酸含有非同源组蛋白H4基板。与以前报道的古细菌和真核生物的sirtuin结构的比较揭示了最大的变异性在一个小的锌结合域牵连发挥特别重要的作用，底物特异性结合的sirtuin蛋白质。cobB/组蛋白H4复合物与其他沉默调节蛋白与含乙酰基-赖氨酸的底物的复合物的比较进一步表明，与乙酰基-赖氨酸侧链的接触和与直接位于乙酰基-赖氨酸C-末端的残基的P-折叠相互作用代表了沉默调节蛋白-底物识别的保守特征。使用等温滴定量热法研究来比较cobB对各种同源和非同源的带有乙酰赖氨酸的肽的亲和力，揭示了放热反应，底物之间的差异相对较小。与此相反，类似的研究采用完整的乙酰化Acs蛋白作为底物揭示的结合反应是吸热的，这表明，cobB识别的基板涉及的疏水表面和/或结构重排的埋葬涉及基板区域的乙酰基-赖氨酸结合位点的远端。总之，这些研究表明，底物特异性结合的沉默调节蛋白涉及的贡献，从锌结合域的酶和底物区域的乙酰赖氨酸结合位点的远端。(C)2004爱思唯尔有限公司保留所有权利。
Sirtuins are NAD(+)-dependent protein deacetylase enzymes that are broadly conserved from bacteria to human, and have been implicated to play important roles in gene regulation, metabolism and longevity. cobB is a bacterial sirtuin that deacetylates acetyl-CoA synthetase (Acs) at an active site lysine to stimulate its enzymatic activity. Here, we report the structure of cobB bound to an acetyl-lysine containing non-cognate histone H4 substrate. A comparison with the previously reported archaeal and eukaryotic sirtuin structures reveals the greatest variability in a small zinc-binding domain implicated to play a particularly important role in substrate-specific binding by the sirtuin proteins. Comparison of the cobB/histone H4 complex with other sirtuin proteins in complex with acetyl-lysine containing substrates, further suggests that contacts to the acetyl-lysine side-chain and P-sheet interactions with residues directly C-terminal to the acetyl-lysine represent conserved features of sirtuin-substrate recognition. Isothermal titration calorimetry studies were used to compare the affinity of cobB for a variety of cognate and non-cognate acetyl-lysine-bearing peptides revealing an exothermic reaction with relatively little discrimination between substrates. In contrast, similar studies employing intact acetylated Acs protein as a substrate reveal a binding reaction that is endothermic, suggesting that cobB recognition of substrate involves a burial of hydrophobic surface and/or structural rearrangement involving substrate regions distal to the acetyl-lysine-binding site. Together, these studies suggest that substrate-specific binding by sirtuin proteins involves contributions from the zinc-binding domain of the enzyme and substrate regions distal to the acetyl-lysine-binding site. (C) 2004 Elsevier Ltd. All rights reserved.