Erythromycin resistance phenotypes of E160 site-directed mutants. (Α) The ErmE–RNA structural model suggests hydrogen bonding between E160 and G2057 of rRNA. The basic ridge is colored green, the α4 cleft blue, and the Ade pocket pink. (B) Minimal inhibitory concentrations (MIC) for erythromycin were measured for E. coli cells expressing E160 site-directed mutants. Experiments were conducted as agar dilution without the antibiotic adjuvant phenyl-arginyl-beta-napthylamide (PAβΝ) or as liquid culture microdilution experiments in the presence of PAβΝ. (C) When cells displayed an erythromycin-sensitive phenotype, western blotting was used to verify that ErmE site-directed mutants were expressed and stable.
