Structural flexibility and the positive charges are the key factors in bacterial cell selectivity and membrane penetration of peptoid-substituted analog of Piscidin 1.
Piscidin 1 (Pis-1) is a novel cytotoxic peptide with a cationic alpha-helical structure isolated from the mast cells of hybrid striped bass. In our previous study, we showed that Pis-1[PG] with a substitution of Pro(8) for Gly(8) in Pis-1 had higher bacterial cell selectivity than Pis-1. We designed peptoid residue-substituted peptide, Pis-1[NkG], in which Gly(8) of Pis-1 was replaced with Nlys (Lys peptoid residue). Pis-1[NkG] had higher antibacterial activity and lower cytotoxicity against mammalian cells than Pis-1 and Pis-1[PG]. We determined the tertiary structure of Pis-1[PG] and Pis-1[NkG] in the presence of DPC micelles by NMR spectroscopy. Both peptides had a three-turn helix in the C-terminal region and a bent structure in the center. Pis-1[PG] has a rigid bent structure at Pro(8) whereas Pis-1[NkG] existed as a dynamic equilibrium of two conformers with a flexible hinge structure at Nlys(8). Depolarization of the membrane potential of Staphylococcus aureus and confocal laser-scanning microscopy study revealed that Pis-1[NkG] effectively penetrated the bacterial cell membrane and accumulated in the cytoplasm, whereas Pis-1[PG] did not penetrate the membrane but remained outside or on the cell surface. Introduction of a lysine peptoid at position 8 of Pis-1 provided conformational flexibility and increased the positive charge at the hinge region; both factors facilitated penetration of the bacterial cell membrane and conferred bacterial cell selectivity on Pis-1[NkG].
Kim
Jin-Kyoung
JK
Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, Seoul 143-701, Korea.
Lee
Sung-Ah
SA
Shin
Soyoung
S
Lee
Jee-Young
JY
Jeong
Ki-Woong
KW
Nan
Yong Hai
YH
Park
Yong Sun
YS
Shin
Song Yub
SY
Kim
Yangmee
Y
D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000494:pharmacology; D001419:Bacteria / Q000166:cytology / Q000187:drug effects; D001492:Bass / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002942:Circular Dichroism; D004305:Dose-Response Relationship, Drug; D029941:Fish Proteins / Q000737:chemistry* / Q000494:pharmacology; D005998:Glycine / Q000737:chemistry; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D050296:Microbial Viability / Q000187:drug effects; D018613:Microscopy, Confocal; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D041681:NIH 3T3 Cells; D011392:Proline / Q000737:chemistry; D011487:Protein Conformation; D013211:Staphylococcus aureus / Q000166:cytology / Q000187:drug effects / Q000502:physiology
D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D029941:Fish Proteins; C449802:moronecidin protein, Morone saxatilis; D011392:Proline; D005998:Glycine