NrdR differentially regulates ribonucleotide reductase genes in aerobiosis or anaerobiosis.
Aerobic expression studies are shown in A-C and G, and anaerobic expression studies in D-F and H. P. aeruginosa wild-type strain (black bars), ΔnrdR mutant strain (white bars) and the deficiency-complemented nrdR strain (ΔnrdR+pETS176) (gray bars) bearing the promoter fusions PnrdA-gfp (panel A and D), PnrdJ-gfp (panel B and E) and PnrdD-gfp (panel C and F), were grown as indicated in the material and methods. GFP fluorescence is expressed as arbitrary units subtracting the reads of the control plasmid pETS130. G) and H) Quantitative RT-PCR analysis of genes encoding three different classes of RNR. qRT-PCR was conducted on cDNA synthesized from wild-type, compared with ΔnrdR cells, both grown aerobically (A550 = 0.6) (G) and anaerobically (A550 = 0.6) (H). The means of three independent experiments are displayed, and the error bars represent the positive standard deviation I) dNTPs pool level of aerobic P. aeruginosa wild-type and nrdR mutant cells treated with 10 mM hydroxyurea (HU), measured by DPA assay. DNA contents were normalized with those of wild-type strain. Three independent experiments were performed and the mean ± standard deviation is shown. *, Significantly different compared with the wild-type strain in an unpaired t-test (P<0.05).