Figure 3

Chemical shift perturbations and dynamics changes are correlated. (a) Representative η vs δ _Methyl scatter plots for Met808Cε (top) and Ile131Cδ1 (bottom). δ _Methyl values were determined according to equation (1), see Supporting Information. Pearson’s correlation coefficients (R_P) are given in the upper right corner. Insets show the build-up curves for the ratio of intensities arising from methyl group ¹H triple-quantum “forbidden” experiments³⁶ (I_forbid/I_allow) vs. relaxation delay time for wildtype and mutant Mre11^HLH-ILVM labeled Rad50^NBD. These data were fit to equation (3) to determine the η rates³⁶, as described in the Methods, with errors determined from the covariance matrix of the fit⁴⁸. The coloring of the curves corresponds to the spectra of the mutants in Fig. 2a. (b) Structure of Mre11^HLH-Rad50^NBD showing side chain methyl groups with altered dynamics upon mutation. Red and orange spheres represent methyl groups that become more flexible upon mutation, whereas green and blue spheres represent methyl groups that become more rigid upon mutation. Red and green coloring denotes “Correlated” methyl groups with significant CSPs upon mutation (i.e., the range in δ _Methyl  > 0.13 ppm) that also have a correlation for η vs δ _Methyl of |R_P| > 0.7. Orange and blue coloring denotes “Not Correlated” methyl groups with small CSPs upon mutation (i.e., the range in δ _Methyl  < 0.13 ppm) but have a large difference in η rates between wildtype and the mutants (|η_WT – the average η_mutants| > 8 sec⁻¹).