Identification of the Pseudomonas aeruginosa glmM gene, encoding phosphoglucosamine mutase

A search for a potential algC homologue within the Pseudomonas aeruginosa P AO1 genome database has revealed an open reading frame (ORF) of unknown fun ction, ORF540 in contig 54 (July 1999 Pseudomonas genome release), that the oretically coded for a 445-amino-acid-residue polypeptide (I. M. Tavares, J . H. Leitao, A. M. Fialho, and I. Sa-Correia, Res. Microbiol. 150:105-116, 1999). The product of this gene is here identified as the phosphoglucosamin e mutase (GlmM) which catalyzes the conversion of glucosamine-6-phosphate t o glucosamine-1-phosphate, an essential step in the formation of the cell w all precursor UDP-N-acetylglucosamine. The P. aeruginosa gene has been clon ed into expression vectors and shown to restore normal peptidoglycan biosyn thesis and cell growth of a glmM Escherichia coli mutant strain. The GlmM e nzyme from P. aeruginosa has been overproduced to high levels and purified to homogeneity in a six-histidine-tagged form. Beside its phosphoglucosamin e mutase activity, the P. aeruginosa enzyme is shown to exhibit phosphomann omutase and phosphoglucomutase activities, which represent about 20 and 2% of its GlmM activity, respectively.