title: 2-Oxoglutarate increases the binding affinity of the NtcA (nitrogen control) transcription factor for the Synechococcus glnA promoter.
abstract: The cyanobacterial NtcA global nitrogen regulator belongs to the catabolite activator protein (CAP) family and activates transcription of nitrogen assimilation genes in response to nitrogen step-down. The binding affinity of NtcA towards a DNA fragment carrying the promoter of the glnA gene from Synechococcus sp. PCC 7942, analyzed in vitro by band-shift assay, was increased five-fold by 2-oxoglutarate in the presence of Mg(2+) ions. The 2-oxoglutarate effect peaked at about 0.6 mM, a rather physiological concentration for this compound under nitrogen-limiting conditions, and could be partially reproduced by 3-oxoglutarate but not by oxaloacetate or glutamate. These results suggest 2-oxoglutarate as a signal of the C to N balance of the cells to regulate NtcA activity and provide a new example of regulation in the versatile CAP family of proteins.
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, Avda. Américo Vespucio s/n, E-41092, Sevilla, Spain. flores@cica.es
authors.forename: María Félix
authors.initials: MF
authors.lastname: Vázquez-Bermúdez
authors.forename: Antonia
authors.initials: A
authors.lastname: Herrero
authors.forename: Enrique
authors.initials: E
authors.lastname: Flores
mesh_terms: D001426:Bacterial Proteins; D002413:Cations, Divalent / Q000494:pharmacology; D000458:Cyanobacteria / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005974:Glutamate-Ammonia Ligase / Q000235:genetics*; D007656:Ketoglutaric Acids / Q000494:pharmacology*; D008274:Magnesium / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011485:Protein Binding / Q000187:drug effects; D014157:Transcription Factors / Q000187:drug effects / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002413:Cations, Divalent; D004268:DNA-Binding Proteins; D007656:Ketoglutaric Acids; D014157:Transcription Factors; C075617:ntcA protein, Synechococcus; C081173:glutamine synthetase I; D005974:Glutamate-Ammonia Ligase; D008274:Magnesium