1rya
Crystal Structure of the E. coli GDP-mannose mannosyl hydrolase in complex with GDP and MG
OverviewOverview
GDP-mannose glycosyl hydrolase (GDPMH) catalyzes the hydrolysis of GDP-mannose and GDP-glucose to GDP and sugar by substitution with inversion at C1 of the sugar. The enzyme has a modified Nudix motif and requires one divalent cation for activity. The 1.3 A X-ray structure of the GDPMH-Mg(2+)-GDP complex, together with kinetic, mutational, and NMR data, suggests a mechanism for the GDPMH reaction. Several residues and the divalent cation strongly promote the departure of the GDP leaving group, supporting a dissociative mechanism. Comparison of the GDPMH structure with that of a typical Nudix hydrolase suggests how sequence changes result in the switch of catalytic activity from P-O bond cleavage to C-O bond cleavage. Changes in the Nudix motif result in loss of binding of at least one Mg(2+) ion, and shortening of a loop by 6 residues shifts the catalytic base by approximately 10 A.
About this StructureAbout this Structure
1RYA is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
ReferenceReference
Structure and mechanism of GDP-mannose glycosyl hydrolase, a Nudix enzyme that cleaves at carbon instead of phosphorus., Gabelli SB, Bianchet MA, Azurmendi HF, Xia Z, Sarawat V, Mildvan AS, Amzel LM, Structure. 2004 Jun;12(6):927-35. PMID:15274914 Page seeded by OCA on Sat May 3 08:03:24 2008