A Novel GDP-Mannose Mannosyl Hydrolase Shares Homology with the MutT Family of Enzymes

摘要: The product of the Escherichia coli orf1.9, or yefc, gene (GenBank™ accession number L11721) has been expressed under control a T7 promoter, purified to apparent homogeneity, and identified as novel enzyme that hydrolyzes GDP-mannose GDP-glucose GDP respective hexose. little no activity on other nucleotides, dinucleotides, nucleotide sugars, sugar phosphates. It pH optimum between 9.0 9.5, Km 0.3 mM, Vmax 1.6 μmol min-1 mg-1 for GDP-mannose, it requires divalent cations activity. This 160 amino acids (Mr = 18, 405) contains consensus sequence GX(I/L/V)(E/Q)(X)2ET(X)6R(X)4E(X)2(I/L), characteristic MutT family proteins previously shown form part nucleotide-binding site (Frick, D. N., Weber, J., Abeygunawardana, C., Gittis, A. G., Bessman, M. Mildvan, S.(1995) Biochemistry 34, 5577-5586). A comparison enzymatic reactions catalyzed by mannosyl hydrolase enzymes suggests signature designates nucleoside diphosphate binding catalytic motif.