Modulation of erm methyltransferase activity by peptides derived from phage display

Combinatorial peptide display on phage M13 protein pIII was used to discover peptide sequences that selectively bind to ErmC' methyltransferase from Bacillus subtilis. One peptide, Ac-LSGVIAT-NH(2), inhibited methylation in vitro with a 50% inhibitory concentration of 20 microM. Interestingly, the set of six peptides which inhibited ErmC' stimulated ErmSF, a homologous methyltransferase from Streptomyces fradiae. Thus, Ac-LSGVIAT-NH(2) may not act directly at the catalytic center of ErmC', but may modulate its activity by binding at a structurally unrelated, but functionally linked, site.