Fig. 8

Zn(II) affinity of RcnR and effects of Zn(II) on DNA binding. a Representative (n = 4) magfura-2 absorbance at 325 nm upon titration of magfura-2 (22.6 μM) and RcnR (16.9 μM) with Zn(II). Solid black line is a fit to a model describing competition from RcnR for one molar equivalent of Zn(II). Solid red lines are simulated curves with K _Zn(II) tenfold tighter (not visible) and tenfold weaker than the fitted value. Dashed line is a simulated curve with K _Zn(II) 100-fold weaker. b Representative (n = 4) quin-2 absorbance at 265 nm upon titration of quin-2 (18.0 μM) and RcnR (14.9 μM) with Zn(II). Solid line is a fit to a model describing competition from RcnR for one molar equivalent of Zn(II). Dashed lines are simulated curves with K _Zn(II) tenfold tighter and tenfold weaker than the fitted value. c Anisotropy change upon titration of rcnAPro (10 nM) with apo-RcnR in the presence of 5 mM EDTA (black symbols, n = 3), or Zn(II)-RcnR (orange symbols, n = 3). Symbol shapes represent individual experiments. Data for Zn(II)-RcnR were fit to a model describing a 2:1 RcnR tetramer (non-dissociable):DNA stoichiometry and solid line is a simulated curve using the mean DNA affinity across the experiments shown⁴⁰. Dashed grey line is a simulated curve describing the published apo-RcnR DNA affinity for comparison⁴⁰. d Anisotropy change upon titration of znuAPro (10 nM) with Zn(II)₂-Zur (orange symbols, n = 5). Symbol shapes represent individual experiments. Data were fit to a model describing a 2:1 Zur dimer (non-dissociable):DNA stoichiometry and lines are simulated curves using the mean DNA affinity across the experiments shown