Mechanism of the quorum-quenching lactonase (AiiA) from Bacillus thuringiensis. 2. Substrate modeling and active site mutations.
Mechanism of the quorum-quenching lactonase (AiiA) from Bacillus thuringiensis. 2. Substrate modeling and active site mutations.
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DOI：
10.1021/bi8003704
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发表时间：
2008-07-22
期刊：
影响因子：
2.9
通讯作者：
Fast W
中科院分区：
文献类型：
--
作者：
Momb J;Wang C;Liu D;Thomas PW;Petsko GA;Guo H;Ringe D;Fast W
N-酰基-L-高丝氨酸内酯水解酶(AHL内酯水解酶)因其能够在革兰氏阴性菌中抑制AHL介导的群体感应通路以及与金属β-内酰胺酶超家族中其他酶的关系而引起人们的极大关注。为了阐明AHL内酯酶的详细催化机制，对可能有助于底物结合和催化的残基进行了突变。使用一系列底物对野生型和突变型酶进行了稳态动力学研究。Y194F和D108N两个突变对整体催化作用有显著影响。在酶−产物复合体高分辨结构模型的基础上，用量子力学/分子力学混合方法模拟底物结合取向，探讨Y194F突变的影响。结合所有的实验和计算结果，我们提出了苏云金芽孢杆菌AHL内切酶催化AHL底物开环水解的详细机理。讨论了在相关酶中也发现的机制的几个特征，并可能有助于定义一个进化线索，连接这个机械多样化的超家族的水解酶。
The N-acyl-l-homoserine lactone hydrolases (AHL lactonases) have attracted considerable attention because of their ability to quench AHL-mediated quorum-sensing pathways in Gram-negative bacteria and because of their relation to other enzymes in the metallo-β-lactamase superfamily. To elucidate the detailed catalytic mechanism of AHL lactonase, mutations are made on residues that presumably contribute to substrate binding and catalysis. Steady-state kinetic studies are carried out on both the wild-type and mutant enzymes using a spectrum of substrates. Two mutations, Y194F and D108N, present significant effects on the overall catalysis. On the basis of a high-resolution structural model of the enzyme−product complex, a hybrid quantum mechanical/molecular mechanical method is used to model the substrate binding orientation and to probe the effect of the Y194F mutation. Combining all experimental and computational results, we propose a detailed mechanism for the ring-opening hydrolysis of AHL substrates as catalyzed by the AHL lactonase from Bacillus thuringiensis. Several features of the mechanism that are also found in related enzymes are discussed and may help to define an evolutionary thread that connects the hydrolytic enzymes of this mechanistically diverse superfamily.
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影响因子：
2.9
作者：
Costello, Alison L.;Sharma, Narayan P.;Tierney, David L.
通讯作者：
Tierney, David L.
影响因子：
3
作者：
BROOKS, BR;BRUCCOLERI, RE;KARPLUS, M
通讯作者：
KARPLUS, M
影响因子：
4.4
作者：
JORGENSEN, WL;CHANDRASEKHAR, J;KLEIN, ML
通讯作者：
KLEIN, ML
影响因子：
4.8
作者：
Garrity, JD;Carenbauer, AL;Crowder, MW
通讯作者：
Crowder, MW
影响因子：
2.6
作者：
Lu, X.;Yuan, Y.;Zhou, S. -N.
通讯作者：
Zhou, S. -N.