Three critical regions of the erythromycin resistance methyltransferase, ErmE, are required for function supporting a model for the interaction of Erm family enzymes with substrate rRNA

RNA affinity binding was measured for selected site-directed ErmE mutants. (A) Affinity binding of ErmE variants to an RNA oligonucleotide mimicking 23S rRNA helix 73 was measured by fluorescence polarization utilizing a 5′ fluorescein label on the RNA. (B) A scatter plot of three replicates of each ErmE variant under analysis is shown along with nonlinear regression fits. A single replicate of a titration of pepsin is shown as a negative control (Neg.) for RNA binding.