title: Piscidin-1-analogs with double L- and D-lysine residues exhibited different conformations in lipopolysaccharide but comparable anti-endotoxin activities.
abstract: To become clinically effective, antimicrobial peptides (AMPs) should be non-cytotoxic to host cells. Piscidins are a group of fish-derived AMPs with potent antimicrobial and antiendotoxin activities but limited by extreme cytotoxicity. We conjectured that introduction of cationic residue(s) at the interface of polar and non-polar faces of piscidins may control their insertion into hydrophobic mammalian cell membrane and thereby reducing cytotoxicity. We have designed several novel analogs of piscidin-1 by substituting threonine residue(s) with L and D-lysine residue(s). L/D-lysine-substituted analogs showed significantly reduced cytotoxicity but exhibited either higher or comparable antibacterial activity akin to piscidin-1. Piscidin-1-analogs demonstrated higher efficacy than piscidin-1 in inhibiting lipopolysaccharide (LPS)-induced pro-inflammatory responses in THP-1 cells. T15,21K-piscidin-1 (0.5 mg/Kg) and T15,21dK-piscidin-1 (1.0 mg/Kg) demonstrated 100% survival of LPS (12.0 mg/Kg)-administered mice. High resolution NMR studies revealed that both piscidin-1 and T15,21K-piscidin-1 adopted helical structures, with latter showing a shorter helix, higher amphipathicity and cationic residues placed at optimal distances to form ionic/hydrogen bond with lipid A of LPS. Remarkably, T15,21dK-piscidin-1 showed a helix-loop-helix structure in LPS and its interactions with LPS could be sustained by the distance of separation of side chains of R7 and D-Lys-15 which is close to the inter-phosphate distance of lipid A.
authors.affiliation: Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow-226 031, India.
authors.forename: Amit
authors.initials: A
authors.lastname: Kumar
authors.affiliation: School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.
authors.forename: Mukesh
authors.initials: M
authors.lastname: Mahajan
authors.affiliation: Electron Microscopy Unit, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow-226 031, India.
authors.forename: Bhanupriya
authors.initials: B
authors.lastname: Awasthi
authors.affiliation: Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow-226 031, India.
authors.forename: Anshika
authors.initials: A
authors.lastname: Tandon
authors.affiliation: Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow-226 031, India.
authors.forename: Munesh Kumar
authors.initials: MK
authors.lastname: Harioudh
authors.affiliation: Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow-226 031, India.
authors.forename: Sonal
authors.initials: S
authors.lastname: Shree
authors.affiliation: Microbiology Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow-226 031, India.
authors.forename: Pratiksha
authors.initials: P
authors.lastname: Singh
authors.affiliation: Microbiology Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow-226 031, India.
authors.forename: Praveen Kumar
authors.initials: PK
authors.lastname: Shukla
authors.affiliation: Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow-226 031, India.
authors.forename: Ravishankar
authors.initials: R
authors.lastname: Ramachandran
authors.affiliation: Electron Microscopy Unit, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow-226 031, India.
authors.forename: Kalyan
authors.initials: K
authors.lastname: Mitra
authors.affiliation: School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore.
authors.forename: Surajit
authors.initials: S
authors.lastname: Bhattacharjya
authors.affiliation: Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow-226 031, India.
authors.forename: Jimut Kanti
authors.initials: JK
authors.lastname: Ghosh
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage; D023181:Antimicrobial Cationic Peptides / Q000008:administration & dosage* / Q000737:chemistry*; D002460:Cell Line; D029941:Fish Proteins / Q000008:administration & dosage* / Q000737:chemistry*; D007249:Inflammation / Q000139:chemically induced / Q000188:drug therapy; D008070:Lipopolysaccharides / Q000008:administration & dosage / Q000037:antagonists & inhibitors*; D008239:Lysine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000737:chemistry*; D051379:Mice
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D029941:Fish Proteins; D008070:Lipopolysaccharides; C449802:moronecidin protein, Morone saxatilis; D008239:Lysine