Abstract
Metabolic pathways for amino sugars (N-acetylglucosamine; GlcNAc and glucosamine; Gln) are essential and remain largely conserved in all three kingdoms of life, i.e., microbes, plants and animals. Upon uptake, in the cytoplasm these amino sugars undergo phosphorylation by phosphokinases and subsequently deacetylation by the enzyme N-acetylglucosamine 6-phosphate deacetylase (nagA) to yield glucosamine-6-phosphate and acetate, the first committed step for both GlcNAc assimilation and amino-sugar-nucleotides biosynthesis. Here we report the cloning of a DNA fragment encoding a partial nagA gene and its implications with regard to amino sugar metabolism in the cellulose producing bacterium Glucoacetobacter xylinus (formally known as Acetobacter xylinum). For this purpose, nagA was disrupted by inserting tetracycline resistant gene (nagA::tetr; named as ΔnagA) via homologous recombination. When compared to glucose fed conditions, the UDP-GlcNAc synthesis and bacterial growth (due to lack of GlcNAc utilization) was completely inhibited in nagA mutants. Interestingly, that inhibition occured without compromising cellulose production efficiency and its molecular composition under GlcNAc fed conditions. We conclude that nagA plays an essential role for GlcNAc assimilation by G. xylinus thus is required for the growth and survival for the bacterium in presence of GlcNAc as carbon source. Additionally, G. xylinus appears to possess the same molecular machinery for UDP-GlcNAc biosynthesis from GlcNAc precursors as other related bacterial species.
Highlights
N-acetylglucosamine (GlcNAc) is a major component of structural polymers in bacteria, plants, and animals [1]
We report a genomic DNA fragment belonging to N-acetylglucosamine 6-phosphate deacetylase from cellulose producing bacterium G. xylinus
We sought to investigate the role of N-acetylglucosamine 6phosphate deacetylase (nagA) in N-acetylglucosamine assimilation in G. xylinus by disrupting nagA
Summary
N-acetylglucosamine (GlcNAc) is a major component of structural polymers in bacteria, plants, and animals [1]. The product of these pathways UDP-GlcNAc, is a ubiquitous and essential metabolite and plays important roles in several metabolic processes [12] In bacteria, it is known as a major cytoplasmic precursor of cell wall peptidoglycan and the disaccharide moiety of some lipids [13]. It is known as a major cytoplasmic precursor of cell wall peptidoglycan and the disaccharide moiety of some lipids [13] In eukaryotes, it serves as the substrate for chitin synthase, whose product chitin is a essential structural component for fungal cell wall [14]. It is used in the GlcNAc moiety of Nlinked glycosylation and the GPI-anchor of cellular membrane proteins [15]
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