Structural highlights
Publication Abstract from PubMedAldose-aldose oxidoreductase ( Cc AAOR) is a recently characterized enzyme from the bacterial strain of Caulobacter crescentus CB15 belonging to the Gfo/Idh/MocA protein family. Cc AAOR catalyzes the oxidation and reduction of a panel of aldose monosaccharides using a tightly bound NADP(H) cofactor that is regenerated in the catalytic cycle. Furthermore, Cc AAOR can also oxidize 1,4-linked oligosaccharides. Here, we present novel crystal structures of the dimeric Cc AAOR in complex with the cofactor and glycerol, D-xylose, D-glucose, maltotriose, and D-sorbitol determined to 2.0, 1.8, 1.7, 1.9, and 1.8 A resolutions, respectively. These complex structures allowed for a detailed analysis of the ligand-binding interactions. The structures showed that the C1 carbon of a substrate, which is either reduced or oxidized, is close to the reactive C4 carbon of the nicotinamide ring of NADP(H). In addition, the O1 hydroxyl group of the substrate, which is either protonated or deprotonated, is unexpectedly close to both Lys-104 and Tyr-189, which may both act as a proton donor or acceptor. This led us to hypothesize that this intriguing feature could be beneficial for Cc AAOR to catalyze the reduction of a linear form of a monosaccharide substrate and the oxidation of a pyranose form of the same substrate in a reaction cycle, during which the bound cofactor is regenerated. Structure and Function of Caulobacter crescentus Aldose-aldose Oxidoreductase.,Taberman H, Andberg M, Koivula A, Hakulinen N, Penttila M, Rouvinen J, Parkkinen T Biochem J. 2015 Oct 5. pii: BJ20150681. PMID:26438878[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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