Structure-based design of peptide inhibitors of botulinum neurotoxin serotype A proteolytic activity

Abstract

P1'arginine of the substrate SNAP-25 is an absolute requirement for catalysis, and the active site of botulinum neurotoxin serotype A (BoNT/A) is populated by acidic residues. We reasoned that arginine derivatives, and basic peptides might bind to the proteolytic domain, and act as inhibitors. A systematic investigation of amino acids, derivatives and basic peptides provided proofs of our concept. D-arginine, arginine hydroxamate and basic peptides effectively inhibited BoNT/A activity. Optimisation of the peptide inhibitors resulted in a RRGC tetrapeptide displaying 90% inhibition at 20 microM. Our studies provide an inhibitor scaffold for potential development as a BoNT/A drug candidate.