Статья

Mechanism of the Quorum-Quenching Lactonase (AiiA) from<i>Bacillus thuringiensis</i>. 2. Substrate Modeling and Active Site Mutations

Jessica MombDivision of Medicinal Chemistry, College of Pharmacy, Graduate Program in Biochemistry, and Texas Institute for Drug and Diagnostic Development, The University of Texas, Austin, Texas 78712, Departments of Chemistry and Biochemistry and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454-9110, and Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131Canhui WangBrandeis UniversityDali LiuDivision of Medicinal Chemistry, College of Pharmacy, Graduate Program in Biochemistry, and Texas Institute for Drug and Diagnostic Development, The University of Texas, Austin, Texas 78712, Departments of Chemistry and Biochemistry and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454-9110, and Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131Pei W. ThomasDivision of Medicinal Chemistry, College of Pharmacy, Graduate Program in Biochemistry, and Texas Institute for Drug and Diagnostic Development, The University of Texas, Austin, Texas 78712, Departments of Chemistry and Biochemistry and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454-9110, and Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131Gregory A. PetskoDivision of Medicinal Chemistry, College of Pharmacy, Graduate Program in Biochemistry, and Texas Institute for Drug and Diagnostic Development, The University of Texas, Austin, Texas 78712, Departments of Chemistry and Biochemistry and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454-9110, and Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131Hua GuoDivision of Medicinal Chemistry, College of Pharmacy, Graduate Program in Biochemistry, and Texas Institute for Drug and Diagnostic Development, The University of Texas, Austin, Texas 78712, Departments of Chemistry and Biochemistry and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454-9110, and Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131Dagmar RingeDivision of Medicinal Chemistry, College of Pharmacy, Graduate Program in Biochemistry, and Texas Institute for Drug and Diagnostic Development, The University of Texas, Austin, Texas 78712, Departments of Chemistry and Biochemistry and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454-9110, and Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131Walter FastDivision of Medicinal Chemistry, College of Pharmacy, Graduate Program in Biochemistry, and Texas Institute for Drug and Diagnostic Development, The University of Texas, Austin, Texas 78712, Departments of Chemistry and Biochemistry and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454-9110, and Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131

2008en

ABI

Аннотация

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-beta-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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Идентификаторы

DOI: 10.1021/bi8003704

Цитирования и источники

Цитирований: 2Использованных источников: 0

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