Effect of fusidic acid (FA) on EF-G function on the ribosome. (A) Inhibition of post-termination complex disassembly. Post-termination complex was rapidly mixed with EF-G/RRF as in Figure 3A in the absence (1) and presence (2) of FA (200 μM), and ribosome disassembly was monitored by light scattering (LS). (B) Dependence of the inhibition on FA concentration. Post-termination complex disassembly by EF-G/RRF was measured as in A at various concentrations of FA (●); 50% inhibition was observed at 0.1 μM FA. For comparison, the inhibition of EF-G turnover in translocation is shown (○); 50% inhibition was observed at ∼200 μM FA. (C) Time course of translocation in the absence and presence of FA. Translocation was monitored by the fluorescence of fluorescence-labeled peptidyl-tRNA (Materials and Methods).
