2y4k

MANNOSYLGLYCERATE SYNTHASE IN COMPLEX WITH MG-GDP

spinqualitylabelsall models 2y4k, resolution 2.45Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2y4k is a 2 chain structure with sequence from Rhodothermus marinus DSM 4252. This structure supersedes the now removed PDB entry 2xw3. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.45Å Ligands: CL, FMT, GDP, MG, TRS Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function D0MI02_RHOM4 Publication Abstract from PubMed The enzymatic transfer of the sugar mannose from activated sugar donors is central to the synthesis of a wide range of biologically significant polysaccharides and glycoconjugates. In addition to their importance in cellular biology, mannosyltransferases also provide model systems with which to study catalytic mechanisms of glycosyl transfer. Mannosylglycerate synthase (MGS) catalyzes the synthesis of alpha-mannosyl-D-glycerate using GDP-mannose as the preferred donor species, a reaction that occurs with a net retention of anomeric configuration. Past work has shown that the Rhodothermus marinus MGS, classified as a GT78 glycosyltransferase, displays a GT-A fold and performs catalysis in a metal ion-dependent manner. MGS shows very unusual metal ion dependences with Mg(2+) and Ca(2+) and, to a lesser extent, Mn(2+), Ni(2+), and Co(2+), thus facilitating catalysis. Here, we probe these dependences through kinetic and calorimetric analyses of wild-type and site-directed variants of the enzyme. Mutation of residues that interact with the guanine base of GDP are correlated with a higher k(cat) value, whereas substitution of His-217, a key component of the metal coordination site, results in a change in metal specificity to Mn(2+). Structural analyses of MGS complexes not only provide insight into metal coordination but also how lactate can function as an alternative acceptor to glycerate. These studies highlight the role of flexible loops in the active center and the subsequent coordination of the divalent metal ion as key factors in MGS catalysis and metal ion dependence. Furthermore, Tyr-220, located on a flexible loop whose conformation is likely influenced by metal binding, also plays a critical role in substrate binding. Substrate and metal ion promiscuity in mannosylglycerate synthase.,Nielsen MM, Suits MD, Yang M, Barry CS, Martinez-Fleites C, Tailford LE, Flint JE, Dumon C, Davis BG, Gilbert HJ, Davies GJ J Biol Chem. 2011 Apr 29;286(17):15155-64. Epub 2011 Feb 2. PMID:21288903 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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