title: Lipopolysaccharide-bound structure of the antimicrobial peptide cecropin P1 determined by nuclear magnetic resonance spectroscopy.
abstract: Antimicrobial peptides (AMPs) are components of the innate immune system and may be potential alternatives to conventional antibiotics because they exhibit broad-spectrum antimicrobial activity. The AMP cecropin P1 (CP1), isolated from nematodes found in the stomachs of pigs, is known to exhibit antimicrobial activity against Gram-negative bacteria. In this study, we investigated the interaction between CP1 and lipopolysaccharide (LPS), which is the main component of the outer membrane of Gram-negative bacteria, using circular dichroism (CD) and nuclear magnetic resonance (NMR). CD results showed that CP1 formed an α-helical structure in a solution containing LPS. For NMR experiments, we expressed (15) N-labeled and (13) C-labeled CP1 in bacterial cells and successfully assigned almost all backbone and side-chain proton resonance peaks of CP1 in water for transferred nuclear Overhauser effect (Tr-NOE) experiments in LPS. We performed (15) N-edited and (13) C-edited Tr-NOE spectroscopy for CP1 bound to LPS. Tr-NOE peaks were observed at the only C-terminal region of CP1 in LPS. The results of structure calculation indicated that the C-terminal region (Lys15-Gly29) formed the well-defined α-helical structure in LPS. Finally, the docking study revealed that Lys15/Lys16 interacted with phosphate at glucosamine I via an electrostatic interaction and that Ile22/Ile26 was in close proximity with the acyl chain of lipid A.
authors.affiliation: Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan.
authors.forename: Mi-Hwa
authors.initials: MH
authors.lastname: Baek
authors.affiliation: Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan.|Faculty of Advanced Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan.
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Kamiya
authors.affiliation: Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kushibiki
authors.affiliation: Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan.
authors.forename: Taichi
authors.initials: T
authors.lastname: Nakazumi
authors.affiliation: Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tomisawa
authors.affiliation: Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan.
authors.forename: Chiharu
authors.initials: C
authors.lastname: Abe
authors.affiliation: Graduate School of Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kumaki
authors.affiliation: Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan.|Faculty of Advanced Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kikukawa
authors.affiliation: Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan.|Faculty of Advanced Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Demura
authors.affiliation: Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan.|Faculty of Advanced Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan.|Chitose Institute of Science and Technology, 758-65 Bibi, Chitose, Hokkaido, 066-8655, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Kawano
authors.affiliation: Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan.|Faculty of Advanced Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810, Japan.
authors.forename: Tomoyasu
authors.initials: T
authors.lastname: Aizawa
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D002236:Carbohydrate Conformation; D004926:Escherichia coli / Q000187:drug effects; D008070:Lipopolysaccharides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008826:Microbial Sensitivity Tests; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry* / Q000494:pharmacology; D011485:Protein Binding; D017433:Protein Structure, Secondary
chemical_list: D000900:Anti-Bacterial Agents; D008070:Lipopolysaccharides; D010455:Peptides; C070016:cecropin P1-LI
keywords: antimicrobial peptide; cecropin P1; lipopolysaccharide; nuclear magnetic resonance; transferred nuclear Overhauser effect