Nitrogen regulation in Sinorhizobium meliloti probed with whole genome arrays.
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+-translocating 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.
Davalos
Marcela
M
Laboratoire des Interactions Plantes-Microorganismes, UMR 2594 INRA-CNRS, Chemin de Borde-Rouge, BP 27, 31326 Castanet-Tolosan Cedex, France.
Fourment
Joëlle
J
Lucas
Antoine
A
Bergès
Hélène
H
Kahn
Daniel
D
D001426:Bacterial Proteins / Q000502:physiology; D002244:Carbon / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D009584:Nitrogen / Q000378:metabolism*; D009876:Operon; D051922:PII Nitrogen Regulatory Proteins; D016962:Sinorhizobium meliloti / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000502:physiology; D014157:Transcription Factors / Q000502:physiology
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D051922:PII Nitrogen Regulatory Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D002244:Carbon; D009584:Nitrogen