Cyanylated Cysteine Used To Map Membrane Binding and Inter-Peptide Contacts in a Model Antimicrobial Peptide

Abstract

Using single-cysteine mutants of the potent antimicrobial peptide CM15 as a model system for binding at the membrane surface, we are developing an infrared probe to characterize site-specific side chain solvent exposure and the ps-time scale dynamics of both membrane-peptide interactions and peptide-peptide contacts. The selective cyanylation of a mutated cysteine residue covalently attaches a nitrile vibrational probe at the chosen site. The frequency and lineshape of the CN stretching vibration are sensitive to both solvent exposure and peptide aggregation. These sensitivities are applied at multiple label sites to reveal information about the structural aspects of CM15's perturbation of E. coli lipid bilayers.