|Gene:||ptmA||Accession Number: G-12599 (MetaCyc)|
Component of: D-glucosamine-6-phosphate synthase (extended summary available)
Gene Citations: [Schoenhofen09]
|Map Position: [1,258,919 -> 1,259,689]|
Molecular Weight of Polypeptide: 28.668 kD (from nucleotide sequence)
Subunit of: D-glucosamine-6-phosphate synthase
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: 18.104.22.168
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, 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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