|Gene:||ptmF||Accession Number: G-12600 (MetaCyc)|
Component of: D-glucosamine-6-phosphate synthase (extended summary available)
Gene Citations: [Schoenhofen09]
|Map Position: [1,257,314 -> 1,258,219]|
Molecular Weight of Polypeptide: 35.003 kD (from nucleotide sequence)
Subunit of: D-glucosamine-6-phosphate synthase
Subunit composition of
D-glucosamine-6-phosphate synthase = [PtmF][PtmA]
L-glutamine-D-fructose-6-phosphate isomerase subunit = PtmF
L-glutamine-D-fructose-6-phosphate transaminase subunit = PtmA
In the food-borne pathogen Campylobacter jejuni this enzyme participates in the biosynthesis of CMP-N,N'-diacetyllegionaminate (CMP-legionaminic acid), a virulence-associated, cell surface sialic acid-like derivative (see pathway CMP-legionaminate biosynthesis I). It converts the starting compound β-D-fructofuranose 6-phosphate to D-glucosamine 6-phosphate in a combined transamination and isomerization reaction (in [Schoenhofen09]).
Recombinant, C-terminal His6-tagged PtmA and recombinant, N-terminal His6-tagged PtmF were purified and characterized. The enzyme appeared to function as a heterodimer of PtmA and PtmF, although the subunit coefficients have not been reported. PtmF and PtmA were found to efficiently convert β-D-fructofuranose 6-phosphate to D-glucosamine 6-phosphate. The isomerase PtmF was stabilized by copurification with glutaminase PtmA, and together they constituted an unfused D-glucosamine-6-phosphate synthase. This is in contrast to the homodimeric GlmS of Escherichia coli, a key enzyme of hexosamine metabolism (see L-glutamine:D-fructose-6-phosphate aminotransferase) [Schoenhofen09].
In "one pot" enzymatic reactions, PtmF, PtmA, PgmL and PtmE converted β-D-fructofuranose 6-phosphate to GDP-D-glucosamine in the CMP-legionaminic acid biosynthetic pathway. Metabolites were purified and identified by capillary electrophoresis/mass spectrometry analysis and NMR spectroscopy [Schoenhofen09].
Enzymatic reaction of: D-glucosamine-6-phosphate synthase
Synonyms: L-glutamine-D-fructose-6-phosphate transaminase (isomerizing)
EC Number: 18.104.22.168β-D-fructofuranose 6-phosphate + L-glutamine ⇄ D-glucosamine 6-phosphate + L-glutamate
The direction shown, i.e. which substrates are on the left and right sides, is in accordance with the direction in which it was curated.
This reaction is reversible.
In Pathways: CMP-legionaminate biosynthesis I
PtmF and PtmA efficiently converted β-D-fructofuranose 6-phosphate to D-glucosamine 6-phosphate as determined by 1H NMR spectroscopy. In the absence of L-glutamine, D-glucopyranose 6-phosphate was produced [Schoenhofen09].
Schoenhofen09: Schoenhofen IC, Vinogradov E, Whitfield DM, Brisson JR, Logan SM (2009). "The CMP-legionaminic acid pathway in Campylobacter: biosynthesis involving novel GDP-linked precursors." Glycobiology 19(7);715-25. PMID: 19282391
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