title: Impact of single-residue mutations on the structure and function of ovispirin/novispirin antimicrobial peptides.
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.
authors.affiliation: Department of Microbiology, University of Iowa College of Medicine, Iowa City 52242, USA.
authors.forename: Monali V
authors.initials: MV
authors.lastname: Sawai
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Waring
authors.forename: William R
authors.initials: WR
authors.lastname: Kearney
authors.forename: Paul B
authors.initials: PB
authors.lastname: McCray
authors.forename: William R
authors.initials: WR
authors.lastname: Forsyth
authors.forename: Robert I
authors.initials: RI
authors.lastname: Lehrer
authors.forename: Brian F
authors.initials: BF
authors.lastname: Tack
mesh_terms: D019943:Amino Acid Substitution; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000235:genetics*; D002470:Cell Survival / Q000187:drug effects; D015195:Drug Design; D004912:Erythrocytes / Q000187:drug effects; D006461:Hemolysis; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D009154:Mutation; D011487:Protein Conformation / Q000187:drug effects; D012996:Solutions; D013329:Structure-Activity Relationship; D013682:Teichoic Acids / Q000494:pharmacology; D014270:Trifluoroethanol / Q000494:pharmacology
chemical_list: D023181:Antimicrobial Cationic Peptides; D008070:Lipopolysaccharides; D012996:Solutions; D013682:Teichoic Acids; C466663:novispirin G10; C440189:ovispirin; C009900:lipoteichoic acid; D014270:Trifluoroethanol