1MOR

ISOMERASE DOMAIN OF GLUCOSAMINE 6-PHOSPHATE SYNTHASE COMPLEXED WITH GLUCOSE 6-PHOSPHATE

Summary for 1MOR

• Entry DOI: 10.2210/pdb1mor/pdb
• Descriptor: GLUCOSAMINE 6-PHOSPHATE SYNTHASE, 6-O-phosphono-alpha-D-glucopyranose (3 entities in total)
• Functional Keywords: glutamine amidotransferase
• Biological source: Escherichia coli
• Cellular location: Cytoplasm: P17169
• Total number of polymer chains: 1
• Total formula weight: 40617.14

Authors

Teplyakov, A. (deposition date: 1997-04-12, release date: 1998-10-07, Last modification date: 2024-02-14)

Primary citation

Teplyakov, A.,Obmolova, G.,Badet-Denisot, M.A.,Badet, B.
The mechanism of sugar phosphate isomerization by glucosamine 6-phosphate synthase.
Protein Sci., 8:596-602, 1999

PubMed Abstract: 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.

PubMed: 10091662

Experimental method

X-RAY DIFFRACTION (1.9 Å)