Figure 1: Cryo-EM structure and molecular model of the B. subtilis MifM-stalled ribosome complex.
From: Structure of the Bacillus subtilis 70S ribosome reveals the basis for species-specific stalling
(a,b) Schematic of the mifM-yidC2 mRNA illustrating the N-terminal transmembrane (TM) segment (black, helix) and C-terminal stalling region (green) of the MifM leader peptide with the stem-loop structure that sequesters the ribosome-binding site (RBS) of the yidC2 gene (blue). In (b) the multisite ribosome stalling (0, +1, +2 and +3) during translation of MifM maintains the unfolded conformation of the mRNA allowing ribosome binding and induction of yidC2 expression. The MifM stalling sequence (residues 69–89) is shown with critical residues boxed in green. Asterisks indicate stop codons. (c) MifM-stalled ribosome complex used for cryo-EM. (d) Transverse section of the cryo-EM structure of the MifM-SRC (30S, yellow; 50S, grey) showing P-tRNA and MifM nascent chain (green) within the ribosomal tunnel and enlargement where ribosomal proteins L4 (cyan) and L22 (orange) are coloured. (e) Electron density (grey mesh) for selected regions of large subunit ribosomal protein and rRNA of the MifM-SRC. (f) Molecular model of the B. subtilis 70S ribosome.
