Divergence of cofactor recognition across evolution:: Coenzyme a binding in a prokaryotic arylamine N-acetyltransferase
Divergence of cofactor recognition across evolution:: Coenzyme a binding in a prokaryotic arylamine N-acetyltransferase
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DOI：
10.1016/j.jmb.2007.10.019
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发表时间：
2008-01-04
影响因子：
5.6
通讯作者：
Noble, Martin E. M.
中科院分区：
文献类型：
--
作者：
Fullam, Elizabeth;Westwood, Isaac M.;Noble, Martin E. M.
芳胺n -乙酰转移酶（NAT）在自然界广泛存在。它们使用乙酰辅酶A （CoA）作为辅助因子对外源性和/或内源性底物进行乙酰化。从哺乳动物到细菌的NAT酶家族结构的保守性已经被一系列的原核NAT结构以及最近报道的人类NAT1的克隆、纯化和结构证明。我们报道了从致病性结核分枝杆菌的近亲海洋分枝杆菌中提取的NAT的动力学表征和晶体结构测定。我们还确定了m.m arinum NAT与CoA复合物的结构，首次揭示了原核生物NAT的辅因子识别。令人惊讶的是，m.m marinum NAT的主要CoA识别位点位于最近沉积的与CoA结合的人类NAT2结构中距离CoA识别位点约30埃的位置。该结构解释了NAT酶的乒乓- Bi-Bi反应机制，并提出了乙酰化酶中间体的保护机制。原核生物NATs在更宽的凹槽中识别辅酶a，表明该亚家族可能比人类NATs容纳更大的底物，并可能有助于识别潜在的内源性底物。这也提示辅助因子结合位点是一个独特的亚位点，可用于针对分枝杆菌中NAT的药物设计。(c) 2007 Elsevier Ltd.版权所有。
Arylamine N-acetyltransferase (NAT) enzymes are widespread in nature. They serve to acetylate xenobiotics and/or endogenous substrates using acetyl coenzyme A (CoA) as a cofactor. Conservation of the architecture of the NAT enzyme family from mammals to bacteria has been demonstrated by a series of prokaryotic NAT structures together with the recently here the cloning, purification, reported structure of human NAT1. We report kinetic characterisation and crystallographic structure determination of NAT from Mycobacterium marinum, a close relative of the pathogenic Mycobacterium tuberculosis. We have also determined the structure of M. marinum NAT in complex with CoA, shedding the first light on cofactor recognition in prokaryotic NATs. Surprisingly, the principal CoA recognition site in M. marinum NAT is located some 30 angstrom from the site of CoA recognition in the recently deposited structure of human NAT2 bound to CoA. The structure explains the Ping-Pong Bi-Bi reaction mechanism of NAT enzymes and suggests mechanisms by which the acetylated enzyme intermediate may be protected. Recognition of CoA in a much wider groove in prokaryotic NATs suggests that this subfamily may accommodate larger substrates than is the case for human NATs and may assist in the identification of potential endogenous substrates. It also suggests the cofactor-binding site as a unique subsite to target in drug design directed against NAT in mycobacteria. (c) 2007 Elsevier Ltd. All rights reserved.