title: A synergism between temporins toward Gram-negative bacteria overcomes resistance imposed by the lipopolysaccharide protective layer.
abstract: Temporins are short and homologous antimicrobial peptides (AMPs) isolated from the frog skin of Rana genus. To date, very little is known about the biological significance of the presence of closely related AMPs in single living organisms. Here we addressed this question using temporins A, B, and L isolated from Rana temporaria. We found that temporins A and B are only weakly active toward Gram-negative bacteria. However, a marked synergism occurs when each is mixed with temporin L. To shed light on the underlying mechanisms involved in these activities, we used various experimental strategies to investigate: (i) the effect of the peptides' interaction on both the viability and membrane permeability of intact bacteria and spheroplasts; (ii) their interaction with lipopolysaccharides (LPS) and the effect of LPS on the oligomeric state of temporins, alone or combining one with another; (iii) their structure in solution and when bound to LPS, by using circular dichroism and ATR-FTIR spectroscopies. Our data reveal that temporin L synergizes with A and B by preventing their oligomerization in LPS. This should promote their translocation across the outer membrane into the cytoplasmic membrane. To the best of our knowledge, this is the first study that explains how a combination of native AMPs from the same species can overcome bacterial resistance imposed by the LPS leaflet.
authors.affiliation: Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Yosef
authors.initials: Y
authors.lastname: Rosenfeld
authors.forename: Donatella
authors.initials: D
authors.lastname: Barra
authors.forename: Maurizio
authors.initials: M
authors.lastname: Simmaco
authors.forename: Yechiel
authors.initials: Y
authors.lastname: Shai
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Mangoni
mesh_terms: D029845:Amphibian Proteins / Q000737:chemistry; D000818:Animals; D023181:Antimicrobial Cationic Peptides; D002462:Cell Membrane / Q000378:metabolism; D002463:Cell Membrane Permeability; D002942:Circular Dichroism; D006090:Gram-Negative Bacteria / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry; D011506:Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D011896:Rana temporaria / Q000378:metabolism*; D012235:Rhodamines / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared; D013997:Time Factors
chemical_list: D029845:Amphibian Proteins; D023181:Antimicrobial Cationic Peptides; D008070:Lipopolysaccharides; D010455:Peptides; D011506:Proteins; D012235:Rhodamines; C104501:temporin