title: NMR structure and binding of esculentin-1a (1-21)NH2 and its diastereomer to lipopolysaccharide: Correlation with biological functions.
abstract: The frog skin-derived antimicrobial peptide esculentin-1a(1-21)NH2 [Esc(1-21)], and its diastereomer Esc(1-21)-1c (containing two D-amino acids at positions 14 and 17), have been recently found to neutralize the toxic effect of Pseudomonas aeruginosa lipopolysaccharide (LPS), although to different extents. Here, we studied the three-dimensional structure of both peptides in complex with P. aeruginosa LPS, by transferred nuclear Overhauser effect spectroscopy. Lack of NOE peaks revealed that both the peptides adopted a random coil structure in aqueous solution. However, Esc(1-21) adopted an amphipathic helical conformation in LPS micelles with 5 basic Lys residues forming a hydrophilic cluster. In comparison, the diastereomer maintained an alpha helical conformation only at the N-terminal region, whereas the C-terminal portion was quite flexible. Isothermal titration calorimetry (ITC) revealed that the interaction of Esc(1-21) with LPS is an exothermic process associated with a dissociation constant of -4μM. In contrast, Esc(1-21)-1c had almost 8 times weaker binding affinity to LPS micelles. Moreover, STD NMR data supported by docking analysis have identified those amino acid residues responsible for the peptide's binding to LPS micelles. Overall, the data provide important mechanistic insights on the interaction of esculentin-derived peptides with LPS and the reason for their different anti-endotoxin activity. These data might also assist to further design more potent antimicrobial peptides with antisepsis properties, which are highly needed to overcome the widespread concern of the available anti-infective agents.
authors.affiliation: Department of Biophysics, Bose Institute, P-1/12, CIT Scheme VII (M), Kolkata 700054, India.
authors.forename: Anirban
authors.initials: A
authors.lastname: Ghosh
authors.affiliation: Department of Biophysics, Bose Institute, P-1/12, CIT Scheme VII (M), Kolkata 700054, India.
authors.forename: Swapna
authors.initials: S
authors.lastname: Bera
authors.affiliation: Department of Biological Chemistry, The Weizmann Institute of Science, 76100 Rehovot, Israel.
authors.forename: Yechiel
authors.initials: Y
authors.lastname: Shai
authors.affiliation: Instituto Pasteur-Fondazione Cenci Bolognetti, Department of Biochemical Sciences, Sapienza University of Rome, Via degli Apuli 9, 00185 Rome, Italy.
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Mangoni
authors.affiliation: Department of Biophysics, Bose Institute, P-1/12, CIT Scheme VII (M), Kolkata 700054, India. Electronic address: anirbanbhunia@gmail.com.
authors.forename: Anirban
authors.initials: A
authors.lastname: Bhunia
mesh_terms: D029845:Amphibian Proteins / Q000737:chemistry*; D000890:Anti-Infective Agents / Q000737:chemistry; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008070:Lipopolysaccharides / Q000737:chemistry*; D008823:Micelles; D062105:Molecular Docking Simulation; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D011550:Pseudomonas aeruginosa / Q000737:chemistry*
chemical_list: D029845:Amphibian Proteins; D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D008070:Lipopolysaccharides; D008823:Micelles; D010455:Peptides; C092874:esculentin protein, Rana esculenta
keywords: (31)P NMR; Antimicrobial peptide; ITC; LPS; STD; tr-NOESY