Fig. 7. AimR peptide selectivity.

a Close view of AimPs bound at the corresponding binding sites AimR^Kat (left) and AimR^SPβ (centre) showing the AimPs and the AimR interacting residues in sticks. The AimR structural elements where the recognition residues are placed are shown in translucent cartoon and labelled. Conserved and variable interacting residues between both AimRs are labelled in black and red, respectively. In the right, the superimposition of both AimPs is shown in stick as well the side-chain for the residue in position 273. The distance between the side chains of AimR^Kat N273 and AimP^SPβ P3 is indicated. b–d Mutation of AimR^Kat residue 273 alter AimP sensitivity. In (b) thermal unfolding curves of AimR^Kat wt (solid lines) and N273A mutant (broken lines) alone (black) or in presence of AimP^Kat (blue) and AimP^SPβ (red) are shown. The unfolding Tms showed in the table support AimP sensitivity variation induced by the mutation. c ITC measurement of AimR^Kat-N273A binding affinity for AimP^Kat, AimP^SPβ and AimP^Phi. In case of binding, thermogram were adjusted to two-binding site model and the two K_D (K_D1 and K_D2) values, one per monomer in the AimR dimer, are shown. In (d) EMSA analysis shows that both AimP^Kat and AimP^SPβ peptides induce DNA releases for the N273A mutant form of AimR^Kat but only AimP^Kat for the wt form. Both AimR^Kat wt and N273A mutant are insensitive to AimP^Phi. EMSA assays have been repeated independently three times with similar results. Source data are provided as a Source Data file.