Figure 5.

Stability of MexR and mutants as detected by thermal stability and ANS binding measurements. A: ANS binding at 480 nm of MexR wt and mutants labeled as above, analyzed from fluorescence emission as a function of GuHCl concentration. The fluorescence of native MexR-wt (0 M GuHCl) incubated with ANS in the presence of PI- or PII-DNA was slightly higher than without DNA (+7.5 and +7.9%, respectively, data not shown in figure). B: Thermal stability measurements recording the CD ellipticity at 222 nm of MexR-wt (filled circle, black), MexR-L13M (empty rhomb, orange), MexR-R21W (filled rhomb, red), MexR-G58E (filled triangle, green), and MexR-R70W (empty circle, blue).