Center for Structural Genomics of Infectious Diseases, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, United States.
Biochemistry. 2011 Mar 29;50(12):2357-63. doi: 10.1021/bi102020s. Epub 2011 Feb 21.
Dehydroquinate dehydratase (DHQD) catalyzes the third step in the biosynthetic shikimate pathway. We present three crystal structures of the Salmonella enterica type I DHQD that address the functionality of a surface loop that is observed to close over the active site following substrate binding. Two wild-type structures with differing loop conformations and kinetic and structural studies of a mutant provide evidence of both direct and indirect mechanisms of involvement of the loop in substrate binding. In addition to allowing amino acid side chains to establish a direct interaction with the substrate, closure of the loop necessitates a conformational change of a key active site arginine, which in turn positions the substrate productively. The absence of DHQD in humans and its essentiality in many pathogenic bacteria make the enzyme a target for the development of nontoxic antimicrobials. The structures and ligand binding insights presented here may inform the design of novel type I DHQD inhibiting molecules.
脱氢奎宁酸脱水酶（DHQD）催化生物合成莽草酸途径的第三步。我们呈现了三种沙门氏菌属 I 型 DHQD 的晶体结构，这些结构解决了在底物结合后观察到的表面环关闭活性位点的功能。两个具有不同环构象的野生型结构以及突变体的动力学和结构研究提供了证据，证明该环直接和间接参与了底物结合。除了允许氨基酸侧链与底物直接相互作用外，环的闭合还需要关键活性位点精氨酸的构象变化，这反过来又使底物具有生产性。DHQD 在人类中不存在，并且在许多致病性细菌中是必需的，这使得该酶成为开发无毒抗菌药物的目标。这里呈现的结构和配体结合见解可能为新型 I 型 DHQD 抑制分子的设计提供信息。
