Site-directed mutants in the N-terminal basic region and motif X are associated with altered phenotypes in ErmE. (A) An AlphaFold2 model of ErmE suggests that some of the dynamic N-terminal residues form α-helix 0. Superposition of the AlphaFold2 ErmE model onto the model given in Figure 2A indicates α0 forms one wall of the active site. (B) MIC values for erythromycin were measured for E. coli cells expressing ermE site-directed mutants in the basic region and motif X. MIC values were measured from three replicates. The range of MIC values observed is reported. Where one value is listed, all replicates possessed this value. (C) Western blotting of cell lysates was used to detect whether ermE site-directed mutants produced a soluble and stable protein.
