Impact of single-residue mutations on the structure and function of ovispirin/novispirin antimicrobial peptides

Protein Eng. 2002 Mar;15(3):225-32. doi: 10.1093/protein/15.3.225.

Abstract

We studied three model antibacterial peptides that resembled the N-terminal 18 amino acids of SMAP-29, an alpha-helical, antimicrobial peptide of sheep. Although the parent compound, ovispirin-1 (KNLRR IIRKI IHIIK KYG), was potently antimicrobial, it was also highly cytotoxic to human epithelial cells and hemolytic for human erythrocytes. Single residue substitutions to ovispirin-1 yielded two substantially less cytotoxic peptides (novispirins), with intact antimicrobial properties. One of these, novispirin G-10, differed from ovispirin-1 only by containing glycine at position 10, instead of isoleucine. The other, novispirin T-7, contained threonine instead of isoleucine at position 7. We determined the three-dimensional solution structures of all three peptides by circular dichroism spectroscopy and two-dimensional nuclear magnetic resonance spectroscopy. Although all retained an amphipathic helical structure in 2,2,2-trifluoroethanol, they manifested subtle fine-structural changes that evidently impacted their activities greatly. These findings show that simple structural modifications can 'fine-tune' an antimicrobial peptide to minimize unwanted cytotoxicity while retaining its desired activity.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Substitution
  • Antimicrobial Cationic Peptides / chemistry
  • Antimicrobial Cationic Peptides / genetics*
  • Cell Survival / drug effects
  • Drug Design
  • Erythrocytes / drug effects
  • Hemolysis
  • Humans
  • Lipopolysaccharides / pharmacology
  • Mutation*
  • Protein Conformation / drug effects
  • Solutions
  • Structure-Activity Relationship
  • Teichoic Acids / pharmacology
  • Trifluoroethanol / pharmacology

Substances

  • Antimicrobial Cationic Peptides
  • Lipopolysaccharides
  • Solutions
  • Teichoic Acids
  • novispirin G10
  • ovispirin
  • lipoteichoic acid
  • Trifluoroethanol