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Crystal structure of Pyrococcus horikoshii quinolinate synthase (NadA) with bound L-malate and Fe4S4 clusterCrystal structure of Pyrococcus horikoshii quinolinate synthase (NadA) with bound L-malate and Fe4S4 cluster
Structural highlights
FunctionNADA_PYRHO Catalyzes the condensation of iminoaspartate with dihydroxyacetone phosphate to form quinolinate (By similarity). Publication Abstract from PubMedThe 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. Crystal Structures of the Iron-Sulfur Cluster-Dependent Quinolinate Synthase in Complex with Dihydroxyacetone Phosphate, Iminoaspartate Analogues, and Quinolinate.,Fenwick MK, Ealick SE Biochemistry. 2016 Jul 22. PMID:27404889[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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