Fig. 3.

SRCD spectra of the CTR/DNA complex (blue), DNA (red) and CTR (green). Spectra of the individual components are measured with equivalent DNA and CTR concentrations. The dotted spectrum represents the relevant combination of the spectra pertaining to the individual components. (++), (+), (±) and (-) indicate the four main behaviors observed. An example of each behavior is presented. For instance for Hfq-CTR E99A,E100A,E102A/DNA spectra (top left corner, (++), a clear different spectrum is measured (blue) compared to the theoretical addition of the peptide and DNA spectra (dotted line). The same analysis for all other Hfq-CTR mutants with (-) behaviors are presented in Sup. Fig. S5. The qualitative comparison considering amplitude and peak position shifts between theoretical and measured spectra always correlates with EMSA and FTIR results.