title: Investigating the effect of a single glycine to alanine substitution on interactions of antimicrobial peptide latarcin 2a with a lipid membrane.
abstract: Latarcins are linear, α-helical antimicrobial peptides purified from the venom of the Central Asian spider Lachesana tarabaevi, with lytic activity against Gram-positive and Gram-negative bacteria, erythrocytes, and yeast at micromolar concentrations. In this work, we investigated the role of the hinge in latarcin 2a (ltc2a, GLFGKLIKKFGRKAISYAVKKARGKH-COOH), which adopts a helix-hinge-helix conformation in membrane-mimicking environments, on peptide-membrane interactions and its potential effect on the selective toxicity of the peptide. A modified latarcin 2a, ltc2aG11A, obtained by replacing the glycine at position 11 with alanine (ltc2aG11A, GLFGKLIKKFARKAISYAVKKARGKH-COOH), adopts a more rigid structure due to the reduced conformational flexibility. Langmuir monolayer measurements combined with atomic force microscopy and X-ray photoemission electron microscopy (X-PEEM) indicate that both peptides bind and insert preferentially into anionic compared with zwitterionic phospholipid monolayers. Modified ltc2aG11A was found to be more disruptive of supported phospholipid bilayer modeling mammalian cell membrane. However, no considerable difference in lytic activity of the two peptides toward bacterial membrane was found. Overall the data indicate that decrease in the flexibility of ltc2a induced by the modification in the hinge region is likely to increase the peptide's nonspecific interactions with zwitterionic cell membranes and potentially increase its toxicity against eukaryotic cells.
authors: Department of Chemistry, Carleton University, 1125 Colonel By Dr., Ottawa, ON, K1S 5B6, Canada.
authors: Grace
authors: G
authors: Idiong
authors: Amy
authors: A
authors: Won
authors: Annamaria
authors: A
authors: Ruscito
authors: Bonnie O
authors: BO
authors: Leung
authors: Adam P
authors: AP
authors: Hitchcock
authors: Anatoli
authors: A
authors: Ianoul
mesh_terms: D000409:Alanine; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D005998:Glycine; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000378:metabolism*; D017354:Point Mutation; D011485:Protein Binding; D013111:Spider Venoms / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013499:Surface Properties
chemical_list: D023181:Antimicrobial Cationic Peptides; D008051:Lipid Bilayers; D010743:Phospholipids; D013111:Spider Venoms; C531159:latarcin 2a, Lachesana tarabaevi; D000409:Alanine; D005998:Glycine