Fig. 1

a In silico prediction of putative Fur and NtcA boxes in the promoter region of alr2502 (pkn22). The Fur boxes are shown in red and the A/T rich region shaded in grey. The palindromic sequence corresponding to the putative NtcA box is shaded in grey. The transcription start site, deduced from Mitschke J at al, 2011 [12], is indicated by (+1). The −35 and −10 boxes are indicated. b EMSA showing the ability of FurA to bind in vitro the promoter region of pkn22 gene. DNA fragments (100 nM) free (line1) or mixed with recombinant FurA protein at the concentrations indicated at the top of the figure in the presence of Mn²⁺ and DTT were separated on a 4 % PAGE gel. The promoter region of nifJ gene was used as non-specific competitor DNA at a concentration of 200 nM. c EMSA showing the ability of NtcA to bind in vitro the promoter regions of pkn22 gene. DNA fragments free (line1) or mixed with recombinant NtcA protein at the concentrations indicated in the presence (+) or absence (−) of 1 mM 2-OG were separated on a 7 % PAGE gel. The arrows indicate the protein-DNA complexes. This experiment was repeated four times and similar results were obtained