MetaCyc Polypeptide: L-glutamine-D-fructose-6-phosphate transaminase subunit

Gene: ptmA Accession Number: G-12599 (MetaCyc)

Synonyms: Cj1332

Species: Campylobacter jejuni jejuni NCTC 11168 = ATCC 700819

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)

Unification Links: Entrez-gene:905624 , Protein Model Portal:Q0P8S6 , String:192222.Cj1332 , UniProt:Q0P8S6

Relationship Links: InterPro:IN-FAMILY:IPR002198 , InterPro:IN-FAMILY:IPR002347 , InterPro:IN-FAMILY:IPR016040 , Pfam:IN-FAMILY:PF00106 , Prints:IN-FAMILY:PR00080 , Prints:IN-FAMILY:PR00081

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

Created 15-Mar-2011 by Fulcher CA , SRI International

Subunit of: D-glucosamine-6-phosphate synthase

Species: Campylobacter jejuni jejuni NCTC 11168 = ATCC 700819

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].

Created 15-Mar-2011 by Fulcher CA , SRI International

Enzymatic reaction of: D-glucosamine-6-phosphate synthase

Synonyms: L-glutamine-D-fructose-6-phosphate transaminase (isomerizing)

EC Number:

β-D-fructofuranose 6-phosphate + L-glutamine <=> D-glucosamine 6-phosphate + L-glutamate

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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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 19.0 on Thu Oct 8, 2015, biocyc13.