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Characterisation of glutamine fructose-6-phosphate amidotransferase (EC 2.6.1.16) and N-acetylglucosamine metabolism in Bifidobacterium

Aïssi, Eliane; Foley, Sophie; Stolarczyk, Emilie; Mouni, Fadoua; Brassart, Colette; Vidal, Olivier; Aissi, Eliane; Bouquelet, Stéphane; Krzewinski, Frédéric

Authors

Eliane Aïssi

Emilie Stolarczyk

Fadoua Mouni

Colette Brassart

Olivier Vidal

Eliane Aissi

Stéphane Bouquelet

Frédéric Krzewinski



Abstract

Bifidobacterium bifidum, in contrast to other bifido-bacterial species, is auxotrophic for N-acetylglucosamine. Growth experiments revealed assimilation of radiolabelled N-acetylglucosamine in bacterial cell walls and in acetate, an end-product of central metabolism via the bifidobacterial d-fructose-6-phosphate shunt. While supplementation with fructose led to reduced N-acetyl-glucosamine assimilation via the d-fructose-6-phosphate shunt, no significant difference was observed in levels of radiolabelled N-acetylglucosamine incorporated into cell walls. Considering the central role played by glutamine fructose-6-phosphate transaminase (GlmS) in linking the biosynthetic pathway for N-acetylglucosamine to hexose metabolism, the GlmS of Bifidobacterium was characterized. The genes encoding the putative GlmS of B. longum DSM20219 and B. bifidum DSM20082 were cloned and sequenced. Bioinformatic analyses of the predicted proteins revealed 43% amino acid identity with the Escherichia coli GlmS, with conservation of key amino acids in the catalytic domain. The B. longum GlmS was over-produced as a histidine-tagged fusion protein. The purified C-terminal His-tagged GlmS possessed glutamine fructose-6-phosphate amidotransferase activity as demonstrated by synthesis of glucosamine-6-phosphate from fructose-6-phosphate and glutamine. It also possesses an independent glutaminase activity, converting glutamine to glutamate in the absence of fructose-6-phosphate. This is of interest considering the apparently reduced coding potential in bifidobacteria for enzymes associated with glutamine metabolism.

Journal Article Type Article
Acceptance Date Sep 13, 2007
Online Publication Date Oct 18, 2007
Publication Date 2008-02
Deposit Date Jul 21, 2008
Journal Archives of Microbiology
Print ISSN 0302-8933
Electronic ISSN 1432-072X
Publisher BMC
Peer Reviewed Peer Reviewed
Volume 189
Issue 2
Pages 157-167
DOI https://doi.org/10.1007/s00203-007-0307-9
Keywords Bifidobacterium; GlmS; Glutamine fructose-6-phosphate amidotransferase; N-acetylglucosamine; Glutaminase activity;
Public URL http://researchrepository.napier.ac.uk/id/eprint/1739
Publisher URL http://dx.doi.org/10.1007/s00203-007-0307-9