Sequence of steps in translocation (A) and ribosome disassembly (B). The ribosomal subunits are depicted in light blue (50S) and yellow (30S) in the ratcheted (50S tilted) or nonratcheted (50S straight) conformation with the tRNAs (red, P site; green, A site) in hybrid (tilted) or classic (upright) positions. EF-G is colored in blue, RRF in magenta. Different conformations of EF-G are not indicated. In B, it is assumed that ribosome disassembly proceeds through the ratcheted conformation of the ribosome. The inhibition by fusidic acid (FA) of ribosome relocking following tRNA-mRNA movement (A) or of subunit splitting (B) is indicated. The mRNA bound to the 30S subunit is omitted for clarity.
