Channeling of ammonia in glucosamine-6-phosphate synthase

Glucosamine-6-phosphate synthase catalyses the first and rate-limiting step in hexosamine metabolism, converting fructose 6-phosphate into glucosamine 6-phosphate in the presence of glutamine. The crystal structure of the Escherichia coli enzyme reveals the domain organisation of the homodimeric mol...

Full description

Saved in:
Bibliographic Details
Published in:Journal of molecular biology 2001-11, Vol.313 (5), p.1093-1102
Main Authors: Teplyakov, A, Obmolova, G, Badet, B, Badet-Denisot, M A
Format: Article
Language:English
Subjects:
Ammonia - metabolism
Binding Sites
Catalysis
Crystallography, X-Ray
Dimerization
Escherichia coli
Escherichia coli - enzymology
glucosamine-6-phosphate synthase
Glutaminase - chemistry
Glutaminase - metabolism
Glutamine - metabolism
Glutamine-Fructose-6-Phosphate Transaminase (Isomerizing) - chemistry
Glutamine-Fructose-6-Phosphate Transaminase (Isomerizing) - metabolism
Isomerases - chemistry
Isomerases - metabolism
Models, Molecular
Multienzyme Complexes - chemistry
Multienzyme Complexes - metabolism
Nitrogen - metabolism
Protein Structure, Quaternary
Protein Structure, Tertiary
Solvents
Structure-Activity Relationship
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Glucosamine-6-phosphate synthase catalyses the first and rate-limiting step in hexosamine metabolism, converting fructose 6-phosphate into glucosamine 6-phosphate in the presence of glutamine. The crystal structure of the Escherichia coli enzyme reveals the domain organisation of the homodimeric molecule. The 18 A hydrophobic channel sequestered from the solvent connects the glutaminase and isomerase active sites, and provides a means of ammonia transfer from glutamine to sugar phosphate. The C-terminal decapeptide sandwiched between the two domains plays a central role in the transfer. Based on the structure, a mechanism of enzyme action and self-regulation is proposed. It involves large domain movements triggered by substrate binding that lead to the formation of the channel.
ISSN:0022-2836
1089-8638
DOI:10.1006/jmbi.2001.5094