A computer-aided analysis of the Pseudomonas aeruginosa PAO1 genome surrounding the g1mM gene was carried out and the organization of this chromosomal region was compared with the equivalent regions in other gamma-proteobacteria species with the genome sequence available. glmM encodes the enzyme phosphoglucosamine mutase which catalyses the interconversion of glucosamine-6-phosphate into glucosamine-1-phosphate in the biosynthetic pathway leading to the synthesis of UDP-N-acetylglucosamine which is simultaneously a precursor for the biosynthesis of cell-wall peptidoglycan and outer membrane lipopolysaccharide. Northern blot analysis suggests that glmM may be a part of the five-cistron operonic structure composed by the Escherichia coli homologues ftsJ, ftsH,folP, glmM, and tpiA. The secG gene, downstream tpiA, does not make part of this polygenic organization, being actively transcribed as a monocistronic mRNA during transition to the stationary phase of growth. Differently, transcription of genes in the glmM operon is more active in the early exponential phase, decreasing with the increase of cell density during exponential growth and reaching negligible values in stationary phase cells. (C) 2003 Elsevier Science (USA). All rights reserved.