3OOJ

C1A mutant of E. coli GlmS in complex with glucose-6P and glutamate

Summary for 3OOJ

• Entry DOI: 10.2210/pdb3ooj/pdb
• Related: 2BPL 2J6H 2VF4 2VF5
• Descriptor: Glucosamine/fructose-6-phosphate aminotransferase, isomerizing, GLUTAMIC ACID, 6-O-phosphono-alpha-D-glucopyranose, ... (6 entities in total)
• Functional Keywords: ammonia channel, glutamine amidotransferase, transferase
• Biological source: Escherichia coli
• Total number of polymer chains: 8
• Total formula weight: 540587.52

Authors

Mouilleron, S.,Golinelli-Pimpaneau, B. (deposition date: 2010-08-31, release date: 2011-10-19, Last modification date: 2023-09-13)

Primary citation

Mouilleron, S.,Badet-Denisot, M.A.,Pecqueur, L.,Madiona, K.,Assrir, N.,Badet, B.,Golinelli-Pimpaneau, B.
Structural basis for morpheein-type allosteric regulation of Escherichia coli glucosamine-6-phosphate synthase: equilibrium between inactive hexamer and active dimer.
J.Biol.Chem., 287:34533-34546, 2012

PubMed Abstract: The amino-terminal cysteine of glucosamine-6-phosphate synthase (GlmS) acts as a nucleophile to release and transfer ammonia from glutamine to fructose 6-phosphate through a channel. The crystal structure of the C1A mutant of Escherichia coli GlmS, solved at 2.5 Å resolution, is organized as a hexamer, where the glutaminase domains adopt an inactive conformation. Although the wild-type enzyme is active as a dimer, size exclusion chromatography, dynamic and quasi-elastic light scattering, native polyacrylamide gel electrophoresis, and ultracentrifugation data show that the dimer is in equilibrium with a hexameric state, in vitro and in cellulo. The previously determined structures of the wild-type enzyme, alone or in complex with glucosamine 6-phosphate, are also consistent with a hexameric assembly that is catalytically inactive because the ammonia channel is not formed. The shift of the equilibrium toward the hexameric form in the presence of cyclic glucosamine 6-phosphate, together with the decrease of the specific activity with increasing enzyme concentration, strongly supports product inhibition through hexamer stabilization. Altogether, our data allow us to propose a morpheein model, in which the active dimer can rearrange into a transiently stable form, which has the propensity to form an inactive hexamer. This would account for a physiologically relevant allosteric regulation of E. coli GlmS. Finally, in addition to cyclic glucose 6-phosphate bound at the active site, the hexameric organization of E. coli GlmS enables the binding of another linear sugar molecule. Targeting this sugar-binding site to stabilize the inactive hexameric state is therefore suggested for the development of specific antibacterial inhibitors.

PubMed: 22851174
DOI: 10.1074/jbc.M112.380378

Experimental method

X-RAY DIFFRACTION (2.5 Å)