Transcriptome analysis of the Bacillus subtilis ccpA topA(S478P) strain

In this study the isogenic Bacillus subtilis mutant strains ccpA topA+ and ccpA topA(S478P) were analyzed. The S478P suppressor mutation occurred when the ccpA mutant was grown on minimal medium supplemented with glucose and ammonium as single sources of carbon and nitrogen, respectively. Under these conditions, the ccpA mutant is unable to produce enough glutamate for growth, since gltAB, encoding the glutamate synthase, is not expressed. In order to get an insight how the S478P mutation in the DNA topoisomerase I affects expression on a global level, the two strains were subjected to a microarray analysis. Bacteria were cultivated in minimal medium supplemented with glucose and glutamate. The microarray data show that the topA(S478P) mutation results in a global re-direction of the central carbon metabolism that includes glutamate biosynthesis. Cells were grown under vigorous agitation at 37 °C in minimal medium supplemented with glucose and glutamate. Samples were taken at OD600 of 1.0. Microarray hybridizations were performed with RNA from three biological replicates. The individual samples were labeled with Cy5; a reference pool containing equal amounts of RNA from all samples was labeled with Cy3.