Crystal structure of the Mycobacterium tuberculosis dUTPase:: Insights into the catalytic mechanism
Crystal structure of the Mycobacterium tuberculosis dUTPase:: Insights into the catalytic mechanism
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DOI：
10.1016/j.jmb.2004.06.028
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发表时间：
2004-08-06
影响因子：
5.6
通讯作者：
Sawaya, MR
中科院分区：
文献类型：
--
作者：
Chan, S;Segelke, B;Sawaya, MR
结核分枝杆菌dUTP核苷酸水解酶（dUTR）的结构已在1.3埃分辨率下与镁离子和不可水解底物类似物α，β-亚氨基dUTP复合确定。dUTP是一种消耗细胞中潜在毒性浓度的dUTP所必需的酶。鉴于其生物学作用的重要性，已经提出抑制M.结核dUTR可能是治疗人类结核病感染的有效手段。这里提出的晶体结构提供了一些设计特异性M抑制剂的潜力。结核脱氧尿苷酶。该结构还提供了新的见解dUTP水解的机制，通过提供一个准确的代表性的酶-底物复合物，其中包括金属离子和dUTP类似物。该结构表明，镁离子的包含对于稳定α-磷的位置以进行在线亲核攻击是重要的。在不存在镁的情况下，dUTP的α-磷酸可以具有相差4.5埃的两个位置中的任一个。一个短暂有序的C-末端环通过保护一般碱Asp 83不受溶剂的影响从而提高其pK（a），从而反过来激活一个紧密结合的水分子进行亲核攻击，从而进一步帮助催化。金属离子配位的α，β，和γ磷酸基团与三齿的几何结构中观察到的DNA聚合酶β与镁和dNTP类似物复合的晶体结构相同，揭示了催化机制中的一些共同特征。(C)2004 Elsevier Ltd.保留所有权利。
The structure of Mycobacterium tuberculosis dUTP nucleotidohydrolase (dUTPase) has been determined at 1.3 Angstrom resolution in complex with magnesium ion and the non-hydrolyzable substrate analog, alpha,beta-imido dUTP. dUTPase is an enzyme essential for depleting potentially toxic concentrations of dUTP in the cell. Given the importance of its biological role, it has been proposed that inhibiting M. tuberculosis dUTPase might be an effective means to treat tuberculosis infection in humans. The crystal structure presented here offers some insight into the potential for designing a specific inhibitor of the M. tuberculosis dUTPase enzyme. The structure also offers new insights into the mechanism of dUTP hydrolysis by providing an accurate representation of the enzyme-substrate complex in which both the metal ion and dUTP analog are included. The structure suggests that inclusion of a magnesium ion is important for stabilizing the position of the alpha-phosphorus for an in-line nucleophilic attack. In the absence of magnesium, the alpha-phosphate of dUTP can have either of the two positions which differ by 4.5 Angstrom. A transiently ordered C-terminal loop further assists catalysis by shielding the general base, Asp83, from solvent thus elevating its pK(a) so that it might in turn activate a tightly bound water molecule for nucleophilic attack. The metal ion coordinates alpha, beta, and gamma phosphate groups with tridentate geometry identical with that observed in the crystal structure of DNA polymerase beta complexed with magnesium and dNTP analog, revealing some common features in catalytic mechanism. (C) 2004 Elsevier Ltd. All rights reserved.