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Publication Abstract from PubMed

Three high-resolution X-ray crystal structures of malate dehydrogenase (MDH; EC 1.1.1.37) from the methylotroph Methylobacterium extorquens AM1 are presented. By comparing the structures of apo MDH, a binary complex of MDH and NAD(+), and a ternary complex of MDH and oxaloacetate with ADP-ribose occupying the pyridine nucleotide-binding site, conformational changes associated with the formation of the catalytic complex were characterized. While the substrate-binding site is accessible in the enzyme resting state or NAD(+)-bound forms, the substrate-bound form exhibits a closed conformation. This conformational change involves the transition of an alpha-helix to a 310-helix, which causes the adjacent loop to close the active site following coenzyme and substrate binding. In the ternary complex, His284 forms a hydrogen bond to the C2 carbonyl of oxaloacetate, placing it in a position to donate a proton in the formation of (2S)-malate.

Conformational changes on substrate binding revealed by structures of Methylobacterium extorquens malate dehydrogenase.,Gonzalez JM, Marti-Arbona R, Chen JCH, Broom-Peltz B, Unkefer CJ Acta Crystallogr F Struct Biol Commun. 2018 Oct 1;74(Pt 10):610-616. doi:, 10.1107/S2053230X18011809. Epub 2018 Sep 19. PMID:30279311^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.