Synthesis, kinetics and inhibition of Escherichia coli Heptosyltransferase I by monosaccharide analogues of Lipid A.
Synthesis, kinetics and inhibition of Escherichia coli Heptosyltransferase I by monosaccharide analogues of Lipid A.
复制标题
脂质 A 的单糖类似物对大肠杆菌庚糖基转移酶 I 的合成、动力学和抑制作用。
DOI：
10.1016/j.bmcl.2018.01.040
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发表时间：
2018
影响因子：
2.7
通讯作者：
Taylor,ErikaA
中科院分区：
文献类型：
--
作者：
Nkosana,NoreenK;Czyzyk,DanielJ;Siegel,ZarekS;Cote,JoyM;Taylor,ErikaA
革兰氏阴性菌包括大多数引起对预先存在的抗生素具有抗性的感染的微生物。复杂的细胞壁结构有助于它们形成生物膜的能力，这通常与医院获得性感染有关。生物膜通过使细菌能够在诸如紫外线辐射、pH变化和抗生素等恶劣环境中生存来促进抗生素抗性。革兰氏阴性菌的外膜含有脂多糖（LPS），其在粘附于表面和形成生物膜中起作用。这项工作的主要重点是合成糖脂库，该糖脂库被设计为脂质A（LPS的膜包埋部分组分）的简化类似物，作为庚糖基转移酶I（HepI或WaaC，一种糖基转移酶）的底物或抑制剂进行测试参与LPS生物合成的酶）。成功地合成了14个类似物并进行了表征。虽然这些化合物被设计为作为HepI的亲核底物，但它们都表现出对HepI的轻度抑制。抑制机理的动力学表征表明，化合物表现出非竞争性和混合抑制HepI。由于非竞争性和混合抑制均导致酶-底物-抑制剂复合物的形成，因此进行了分子对接研究（使用AutoDock维纳），以鉴定这些化合物的潜在变构结合位点。抑制剂被证明是绑定到口袋后，经历了从开放到封闭的活性位点状态的构象变化形成的。通过变构位点抑制HepI表明蛋白质动力学的破坏可能是抑制HepI和潜在的GT-B结构类的其他酶的可行机制。
Gram-negative bacteria comprise the majority of microbes that cause infections that are resistant to pre-existing antibiotics. The complex cell wall architecture contributes to their ability to form biofilms, which are often implicated in hospital-acquired infections. Biofilms promote antibiotic resistance by enabling the bacteria to survive hostile environments such as UV radiation, pH shifts, and antibiotics. The outer membrane of Gram-negative bacteria contains lipopolysaccharide (LPS), which plays a role in adhesion to surfaces and formation of biofilms. The main focus of this work was the synthesis of a library of glycolipids designed to be simplified analogues of the Lipid A, the membrane embedded portion component of LPS, to be tested as substrates or inhibitors of Heptosyltransferase I (HepI or WaaC, a glycosyltransferase enzyme involved in the biosynthesis of LPS). Fourteen analogues were synthesized successfully and characterized. While these compounds were designed to function as nucleophilic substrates of HepI, they all demonstrated mild inhibition of HepI. Kinetic characterization of inhibition mechanism identified that the compounds exhibited uncompetitive and mixed inhibition of HepI. Since both uncompetitive and mixed inhibition result in the formation of an Enzyme-Substrate-inhibitor complex, molecular docking studies (using AutoDock Vina) were performed, to identify potential allosteric binding site for these compounds. The inhibitors were shown to bind to a pocket formed after undergoing a conformational change from an open to a closed active site state. Inhibition of HepI via an allosteric site suggest that disruption of protein dynamics might be a viable mechanism for the inhibition of HepI and potentially other enzymes of the GT-B structural class.