Modulation of Erm methyltransferase activity by peptides derived from phage display

Combinatorial peptide display on phage M13 protein pIII was used to discove r peptide sequences that selectively bind to ErmC' methyltransferase from B acillus subtilis, One peptide, Ac-LSGVIAT-NH2, inhibited methylation in vit ro with a 50% inhibitory concentration of 20 mu M. Interestingly, the set o f six peptides which inhibited ErmC' stimulated ErmSF, a homologous methylt ransferase from Streptomyces fradiae. Thus, Ac-LSGVIAT-NH2 mag not act dire ctly at the catalytic center of ErmC', but may modulate its activity by bin ding at a structurally unrelated, but functionally linked, site.