Fig. 4: Cryo-EM FBI-GS-GlnR structures reveal GlnR binds in the GS active site.

A Cartoon diagram of the Pp GlnR C-tail (red) binding to GS. GlnR binds in the GS active site between two subunits and at the nexus of the oligomer interface between stacked rings. In this figure one GS subunit is colored green and the other salmon. The active site regions are colored blue and labeled. B Density for GlnR peptide and contacts with GS in the Pp FBI-GS(12)-GlnR complex (map contoured at 0.09 σ). Residues making contacts are labeled and different GS subunits are denoted as GSI, GSII, and GSIII, underscoring that three GS subunits participate in GlnR contacts. C Density for GlnR peptide and contacts with GS in the Pp FBI-GS(14)-GlnR complex (map contoured at 0.06 σ). D Density for GlnR peptide and contacts with GS in the Sa FBI-GS-GlnR complex (map contoured at 0.15 σ). E Density for GlnR peptide and contacts with GS in the Bs FBI-GS-GlnR complex (map contoured at 0.65 σ). F Density for GlnR peptide and contacts with GS in the Lm FBI-GS-GlnR complex (map contoured at 0.55 σ).