Toe-printing analysis was performed using the RST2 template (49 (link)) as previously described (50 (link)). Cell free translation reactions, carried out in the PURExpress in vitro protein synthesis system (New England Biolabs, Ipswich, MA, USA) were supplemented with 50 μM thiostrepton or 100 μM of peptides which were added in water and samples (5 μl volume) were incubated for 15 min at 37°C prior to the primer extension phase of the procedure. The control reaction had no inhibitor. Primer extension was carried out for 15 min, after which the samples were processed as described (50 (link)).