FIG. 9.

DNA binding activities of NirA proteins mutated in the dimerization element. Wild type, NirA(1–121) peptide as described in the legend to Fig. 7. Mutants: L1, Leu91Val; LL2, Leu98Val and Leu99Val; LL3, Leu105Val and Leu106Val. A plus sign between the symbols for each mutation denotes the presence of two or three mutations in the dimerization element. Equal amounts of in vitro-synthesized protein substitutions were incubated with the probe described in the legend to Fig. 6, containing NirA binding site 2. The NirA protein present in the transcription-translation reactions was quantified by Western blot analysis with polyclonal antibodies against the NirA(1–125) peptide followed by densitometry.