Structural basis for catalytic and inhibitory mechanisms of β-hydroxyacyl-acyl carrier protein dehydratase (FabZ)
Structural basis for catalytic and inhibitory mechanisms of β-hydroxyacyl-acyl carrier protein dehydratase (FabZ)
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DOI：
10.1074/jbc.m705566200
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发表时间：
2008-02-29
影响因子：
4.8
通讯作者：
Jiang, Hualiang
中科院分区：
文献类型：
--
作者：
Zhang, Liang;Liu, Weizhi;Jiang, Hualiang
在II型脂肪酸生物合成系统（FAS II）途径中，β -羟基酰基-酰基载体蛋白脱水酶（FabZ）是饱和和不饱和脂肪酸生物合成延伸循环的重要酶。FabZ已成为发现抗病原菌有效化合物的重要靶标。为了表征FabZ的催化和抑制机制，本文研究了幽门螺杆菌（Helicobacter pylori, HpFabZ）的FabZ及其与两种新发现的抑制剂的配合物的晶体结构。不同于其他细菌fabz的结构，HpFabZ在α 3和β 3之间含有一个额外的短的两转α -螺旋（α 4），它在形成底物结合通道中起重要作用。隧道入口残基Tyr-100在晶体结构上呈开式或闭式构象。HpFabZ突变体（Y100A）的晶体结构表征、结合亲和力测定和酶活性测定证实了tyr1 -100在催化活性和底物结合方面的重要性。出口隧道的残留ph -83也被精炼成两种不同的构象，导致隧道形成l形和u形。这些数据有助于进一步了解HpFabZ的催化机理。此外，HpFabZ及其抑制剂的共晶结构表明，HpFabZ的酶活性可以通过占领通道入口或堵塞通道来抑制，以阻止底物进入活性位点。我们的研究为FabZ的催化和抑制机制提供了一些见解，从而促进了抗菌剂的开发。
beta-Hydroxyacyl-acyl carrier protein dehydratase (FabZ) is an important enzyme for the elongation cycles of both saturated and unsaturated fatty acids biosyntheses in the type II fatty acid biosynthesis system (FAS II) pathway. FabZ has been an essential target for the discovery of compounds effective against pathogenic microbes. In this work, to characterize the catalytic and inhibitory mechanisms of FabZ, the crystal structures of the FabZ of Helicobacter pylori (HpFabZ) and its complexes with two newly discovered inhibitors have been solved. Different from the structures of other bacterial FabZs, HpFabZ contains an extra short two-turn alpha-helix (alpha 4) between alpha 3 and beta 3, which plays an important role in shaping the substrate-binding tunnel. Residue Tyr-100 at the entrance of the tunnel adopts either an open or closed conformation in the crystal structure. The crystal structural characterization, the binding affinity determination, and the enzymatic activity assay of the HpFabZ mutant (Y100A) confirm the importance of Tyr-100 in catalytic activity and substrate binding. Residue Phe-83 at the exit tunnel was also refined in two alternative conformations, leading the tunnel to form an L-shape and U-shape. All these data thus contributed much to understanding the catalytic mechanism of HpFabZ. In addition, the co-crystal structures of HpFabZ with its inhibitors have suggested that the enzymatic activity of HpFabZ could be inhibited either by occupying the entrance of the tunnel or plugging the tunnel to prevent the substrate from accessing the active site. Our study has provided some insights into the catalytic and inhibitory mechanisms of FabZ, thus facilitating antibacterial agent development.