2c54 | pdb_00002c54

GDP-MANNOSE-3', 5' -EPIMERASE (ARABIDOPSIS THALIANA), K178R, WITH GDP-BETA-L-GULOSE AND GDP-4-KETO-BETA-L-GULOSE BOUND IN ACTIVE SITE.

spinqualitylabelsall models 2c54, resolution 1.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2c54 is a 2 chain structure with sequence from Arabidopsis thaliana. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: EPE, FMT, GKD, GKE, NAD Related: 2c59, 2c5a, 2c5e Activity: GDP-mannose 3,5-epimerase, with EC number 5.1.3.18 Resources: FirstGlance, OCA, RCSB, PDBsum Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed GDP-mannose-3',5'-epimerase (GME) from Arabidopsis thaliana catalyzes the epimerization of both the 3' and 5' positions of GDP-alpha-D-mannose to yield GDP-beta-L-galactose. Production of the C5' epimer of GDP-alpha-D-mannose, GDP-beta-L-gulose, has also been reported. The reaction occurs as part of vitamin C biosynthesis in plants. We have determined structures of complexes of GME with GDP-alpha-D-mannose, GDP-beta-L-galactose, and a mixture of GDP-beta-L-gulose with GDP-beta-L-4-keto-gulose to resolutions varying from 2.0 to 1.4 A. The enzyme has the classical extended short-chain dehydratase/reductase (SDR) fold. We have confirmed that GME establishes an equilibrium between two products, GDP-beta-L-galactose and GDP-beta-L-gulose. The reaction proceeds by C4' oxidation of GDP-alpha-D-mannose followed by epimerization of the C5' position to give GDP-beta-L-4-keto-gulose. This intermediate is either reduced to give GDP-beta-L-gulose or the C3' position is epimerized to give GDP-beta-L-4-keto-galactose, then C4' is reduced to GDP-beta-L-galactose. The combination of oxidation, epimerization, and reduction in a single active site is unusual. Structural analysis coupled to site-directed mutagenesis suggests C145 and K217 as the acid/base pair responsible for both epimerizations. On the basis of the structure of the GDP-beta-L-gulose/GDP-beta-L-4-keto-gulose co-complex, we predict that a ring flip occurs during the first epimerization and that a boat intermediate is likely for the second epimerization. Comparison of GME with other SDR enzymes known to abstract a protein alpha to the keto function of a carbohydrate identifies key common features. Structure and function of GDP-mannose-3',5'-epimerase: an enzyme which performs three chemical reactions at the same active site.,Major LL, Wolucka BA, Naismith JH J Am Chem Soc. 2005 Dec 28;127(51):18309-20. PMID:16366586 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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