Figure 6.

(a) Cartoon representation of the X-ray structure of full-length wt RfaH (PDB ID: 2OUG). The N-terminal domain (NTD) is shown in grey, while the fold-switching C-terminal domain (CTD) is coloured rainbow. In free full-length RfaH, the CTD is helical. (b) The all-β sheet structure of the CTD of RfaH obtained using NMR spectroscopy (PDB ID: 2LCL). The colour scheme is identical to the CTD in (a). (c) The residues in the NTD (pale pink) important for binding RNA polymerase are shown as sticks on the structure of RfaH and coloured yellow. Most of these residues are sequestered by the helical CTD (cyan) in the free form of RfaH, but become exposed upon fold-switching and detachment of the CTD from the NTD. (d) The residues in the CTD (cyan) important for binding the ribosomal protein S10 are shown as green spheres in both the helical (top) and sheet conformations of the CTD. Most of these residues are also buried at the NTD–CTD interface but become available for binding S10 when the NTD interacts with RNA polymerase.