Expression data from wild type Sinorhizobium meliloti and mutants in the NSR grown under conditions of high and low nitrogen availability

Acquisition and utilization of nitrogen is governed by the Nitrogen Stress Response regulatory cascade. GlnD is the primary nitrogen sensor in this system, and modifies the PII proteins to effect changes in the expression of target genes. We used microarrays to evaluate changes in gene expression due to nitrogen availability, mutation of the glnD gene, and deletion of both PII proteins. Sinorhizobium meliloti cultures were grown at 30C to mid-log phase (0.5–0.6 OD600) for RNA extraction and hybridization on Affymetrix microarrays. Wild-type 1021, a strain containing a mutation in glnD, and a strain with both PII proteins deleted were grown in media containing either 0.05% ammonium chloride or 0.02% sodium glutamate as the nitrogen source.