Figure 5 : MifM stabilizes the uninduced state of the PTC to inhibit A-tRNA accommodation.

From: Structure of the Bacillus subtilis 70S ribosome reveals the basis for species-specific stalling

Figure 5

(a) A-tRNA accommodation leads to conformational changes in U2584 and U2585 shifting the PTC from an uninduced (yellow) to an induced state (salmon)24,25,26. (b) The PTC of the MifM-SRC (grey density with rRNA (blue) and P-tRNA (green)) resembles that of the uninduced state (yellow). (c) Rotation of U2506 is required to accommodate the shift in U2585 that occurs on A-tRNA accommodation24,25,26. (d) E87 of MifM nascent chain (green) occupies the position of the induced state of U2506. (e) A-tRNA accommodation leads to a slight shift in the position of A2602. (f) The position of A2602 (blue) in the MifM-SRC encroaches on the A-tRNA binding site and is distinct from the position of A2602 in the uninduced (yellow) or induced states (pink)24,25,26. (g) A distinct conformation of A2602 (yellow) is required to position the GGQ motif of RF2 at the PTC to catalyse peptidyl-tRNA hydrolysis29,30,31,32. (h) The position of A2602 (blue) in the MifM-SRC is incompatible with the canonical binding position of RF2 at the PTC29,30,31,32.