Dual regulation of nitrogen metabolism by CodY and GlnR in Streptococcus mutans

CodY and GlnR are two major transcriptional regulators in nitrogen metabolism in Gram-positive bacteria. CodY regulates genes involved in the adaptive response to poor growth conditions, especially to nutrient limitation. GlnR controls nitrogen utilization according to the availability of nitrogen source. In this study we used microarray to investigate the regulatory roles that CodY and GlnR play in nitrogen metabolism in Streptococcus mutans. Streptococcus mutans UA159 wild-type cells, ΔcodY, ΔglnR, and ΔcodYglnR strains were grown in a chemically-defined medium until the mid-log phase. The nitrogen source was 1% tryptone. Twenty millimolar sodium thiosulfate was added to the medium to support cysteine biosynthesis. The transcriptional profile of the whole genome was examined with microarray.