FIG. 3.

Overview of C. glutamicum operons preceded by a functional DtxR binding site. The black boxes indicate the positions of the identified DtxR boxes. The mRNA ratios (ΔdtxR mutant versus wild type) obtained from the DNA microarray experiments are shown below the corresponding gene. The first value gives the ratio under iron excess, and the second value gives the ratio under limitation. It has to be taken into account that for the majority of genes the indicated function was derived from the genome annotation rather than from experimental data. The genes/operons were separated in four groups. Group A contains genes whose mRNA level was at least 1.5-fold increased in the ΔdtxR mutant under iron excess. These genes are presumably repressed by DtxR. Group B comprises genes whose mRNA level was at least 1.5-fold decreased in the ΔdtxR mutant under iron excess. These genes might be activated by DtxR. Group C contains two genes whose mRNA levels were almost unaltered in the ΔdtxR mutant under iron excess but were increased under iron limitation. How DtxR controls expression of these genes is not clear yet. Group D contains all genes whose mRNA ratios could not be determined and those whose mRNA levels were altered less than 1.5-fold in the ΔdtxR mutant. Whether these genes are indeed regulated by DtxR requires further studies.