TABLE 2.

Properties of S. coelicolor wild-type and mutant NrdR proteins

NrdR proteinMol of ATP+dATP/mol of proteina% dATP/dATP+ATPbMajor oligomeric statecDNA bindingd
LH
Group 1
    Wild type0.71 (0.35)38L+-
    R51A0.76 (0.26)96L+-
    Y121A0.73 (0.36)96L+-
    K62A0.58 (0.34)57L-
    V63A0.83 (0.35)92H+/--
    Y128A1.56 (0.44)100L+-
Group 2
    V48A0.19 (0.06)82H+-
    K50A0.27 (0.09)91H+-
    E56A0.37 (0.13)100H+-
    ATP-cone0.70 (0.33)25DimerNANA
  • a The amounts of bound ATP and dATP per mole of wild-type and mutant NrdR, determined by protein absorption spectra and nucleotide absorption spectra after PCA treatment (in parentheses), are the average values of two measurements made with two independent protein preparations obtained after Ni2+ affinity chromatography.

  • b The percent dATP of bound nucleotide, determined by Affi-Gel boronate affinity chromatography, is the average value of two to three measurements with the same protein preparations. Individual values differed from the mean by no more than 6%.

  • c The oligomeric state of the wild type and mutant is that of the major protein fraction obtained after Superdex 200 gel filtration chromatography (see Fig. 5), which is denoted as “L” for low-molecular-weight material and “H” for high-molecular-weight aggregated material.

  • d DNA binding refers to the ability of the low- and high-molecular-weight fractions to bind to the probes nrdAB and nrdRJ. +, binding; +/−, weak binding; -, lack of binding. NA, not applicable.