Characterization of the Bradyrhizobium japonicum NtrC regulon by DNA Microarray analysis.

The Bradyrhizobium japonicum NtrC regulatory protein influences gene expression in response to changes in intracellular nitrogen status. Under conditions of low nitrogen, phosphorylation of NtrC results in up-regulation of a number of genes involved in nitrogen metabolism and nitrogen acquisition. To better define the exact nature of NtrC’s influence on gene expression, a ntrC mutation was created in B. japonicum and transcriptional profiling was performed by DNA microarray analysis of both the mutant and wild type strains. Bradyrhizobium japonicum USDA 110 and a ntrC mutant in the USDA 110 background were cultured in minimal medium supplemented with 10mM ammonium and 10mM glutamate as nitrogen sources. Three biological replicates were prepared for each strain and dye swap replications were performed for each hybridization producing a total of six slides.