Crystal Structures of the Iron–Sulfur Cluster-Dependent Quinolinate Synthase in Complex with Dihydroxyacetone Phosphate, Iminoaspartate Analogues, and Quinolinate

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• 作者：Michael K. Fenwick ; Steven E. Ealick
• 刊名：Biochemistry
• 出版年：2016
• 出版时间：August 2, 2016
• 年：2016
• 卷：55
• 期：30
• 页码：4135-4139
• 全文大小：430K
• 年卷期：0
• ISSN：1520-4995

文摘

The quinolinate synthase of prokaryotes and photosynthetic eukaryotes, NadA, contains a [4Fe-4S] cluster with unknown function. We report crystal structures of Pyrococcus horikoshii NadA in complex with dihydroxyacetone phosphate (DHAP), iminoaspartate analogues, and quinolinate. DHAP adopts a nearly planar conformation and chelates the [4Fe-4S] cluster via its keto and hydroxyl groups. The active site architecture suggests that the cluster acts as a Lewis acid in enediolate formation, like zinc in class II aldolases. The DHAP and putative iminoaspartate structures suggest a model for a condensed intermediate. The ensemble of structures suggests a two-state system, which may be exploited in early steps.