Figure 1.
E. coli 70S ribosome I in an intermediate rotated state. (a) Ribosomal subunits of ribosome I colored by atomic displacement factor (ADP) from 20 to 150 Å2. The views are from the perspective of the subunit interface. Features in the 50S subunit include the central protuberance (CP), L1 arm (L1), protein L9 (L9), L7–L12 region (L12), A-site finger (ASF) and the GTPase center (G). In the 30S subunit, these include the head (H), body (B), and platform (PL). (b) Single-molecule imaging of the modulation of ribosome dynamics by magnesium ions. Occupancy of unrotated (red) and rotated (black) states of the ribosome as measured by smFRET between fluorophores on uS13 and uL1, shown with standard deviations of three technical replicates (Online methods).