Nitrogen regulation in Sinorhizobium meliloti probed with whole genome arrays

• Published in: FEMS microbiology letters Vol. 241; no. 1; pp. 33 - 40
• Main Authors: Davalos, M, Fourment, J, Lucas, A, Berges, H, Kahn, D
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.12.2004; Blackwell; Oxford University Press; Wiley-Blackwell
• Subjects: Ammonium; Arrays; Bacterial Proteins - physiology; Bacteriology; Biological and medical sciences; Carbon; Carbon - metabolism; Carbon sources; DNA-Binding Proteins - physiology; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation, Bacterial; Genes; Genome, Bacterial; Genomes; Genomic arrays; Glutamate-ammonia ligase; Glutamine; Life Sciences; Metabolism; Metabolism. Enzymes; Microbiology; Nitrogen; Nitrogen - metabolism; Nitrogen regulation; nitrogen-fixing bacteria; ntr system; Operon; Other; Pentose; Pentose phosphate pathway; PII Nitrogen Regulatory Proteins; Regulators; Sinorhizobium meliloti; Sinorhizobium meliloti - genetics; Sinorhizobium meliloti - metabolism; symbionts; Trans-Activators - physiology; Transcription Factors - physiology; Yeast; Nitrogen regulation; Genomic arrays; system; Energy metabolism; Carbon-nitrogen ligases; Enzyme; Medicago sativa; Nitrogen; Symbiont; Genetic determinism; Regulation(control); Leguminosae; Ligases; Dicotyledones; Angiospermae; Bacteria; Spermatophyta; Fodder crop; Rhizobiaceae; Glutamate-ammonia ligase; Sinorhizobium meliloti
• ISSN: 0378-1097; 1574-6968
• DOI: 10.1016/j.femsle.2004.09.041

Using whole genome arrays, we systematically investigated nitrogen regulation in the plant symbiotic bacterium Sinorhizobium meliloti. The use of glutamate instead of ammonium as a nitrogen source induced nitrogen catabolic genes independently of the carbon source, including two glutamine synthetase genes, various aminoacid transporters and the glnKamtB operon. These responses depended on both the ntrC and glnB nitrogen regulators. Glutamate repressible genes included glutamate synthase and a H(+)-trans-locating pyrophosphate synthase. The smc01041-ntrBC operon was negatively autoregulated in a glnB-dependent fashion, indicating an involvement of phosphorylated NtrC. In addition to the nitrogen response, glutamate remodelled expression of carbon metabolism by inhibiting expression of the Entner-Doudoroff and pentose phosphate pathways, and by stimulating gluconeogenetic genes independently of ntrC.