1mos

From Proteopedia

ISOMERASE DOMAIN OF GLUCOSAMINE 6-PHOSPHATE SYNTHASE COMPLEXED WITH 2-AMINO-2-DEOXYGLUCITOL 6-PHOSPHATE

Overview

Glucosamine 6-phosphate synthase converts fructose-6P into glucosamine-6P, or glucose-6P depending on the presence or absence of glutamine. The, isomerase activity is associated with a 40-kDa C-terminal domain, which, has already been characterized crystallographically. Now the, three-dimensional structures of the complexes with the reaction product, glucose-6P and with the transition state analog 2-amino-2-deoxyglucitol-6P, have been determined. Glucose-6P binds in a cyclic form whereas, 2-amino-2-deoxyglucitol-6P is in an extended conformation. The information, on ligand-protein interactions observed in the crystal structures together, with the isotope exchange and site-directed mutagenesis data allow us to, propose a mechanism of the isomerase activity of glucosamine-6P synthase., The sugar phosphate isomerization involves a ring opening step catalyzed, by His504 and an enolization step with Glu488 catalyzing the hydrogen, transfer from C1 to C2 of the substrate. The enediol intermediate is, stabilized by a helix dipole and the epsilon-amino group of Lys603. Lys485, may play a role in deprotonating the hydroxyl O1 of the intermediate.

About this Structure

1MOS is a Single protein structure of sequence from Escherichia coli with SO4, NA, AGP and MES as ligands. Active as Glutamine--fructose-6-phosphate transaminase (isomerizing), with EC number 2.6.1.16 Full crystallographic information is available from OCA.

Reference

The mechanism of sugar phosphate isomerization by glucosamine 6-phosphate synthase., Teplyakov A, Obmolova G, Badet-Denisot MA, Badet B, Protein Sci. 1999 Mar;8(3):596-602. PMID:10091662

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