Basic switch and hinge region mutations affect Rad50 activity. (a) Bar chart showing the effect of mutation, relative to wildtype activity, for ATP hydrolysis (left - kcat/KM), ATP-dependent dimerization (middle - % dimerization), and Mre11 exonuclease activity (right – relative fluorescence). Green, orange, purple, and blue bars represent wildtype, V156M, V160M, and R805E, respectively. The order of the bars follows the general order of peaks that experience significant CSPs upon mutation. For ATP hydrolysis and exonuclease assays, bars represent the average of at least three independent measurements, and the error bars are the standard deviation of the replicate experiments. Dimerization assays were performed once. *, ** and *** Represent p-values less than 0.05, 0.01, and 0.001, respectively. The inset above shows the CSPs for L47Cδ1. (b) Structure of Mre11HLH-Rad50NBD highlighting the side chain methyl groups that have a |mean[RP,Hydrolysis, RP,Dimerization, RP,Exonuclease]| > 0.65.