Effect of natural L- to D-amino acid conversion on the organization, membrane binding, and biological function of the antimicrobial peptides bombinins H.
Antimicrobial peptides (AMPs) are evolutionarily old components of innate immunity found in all living pluricellular organisms. Interestingly, some organisms express families of AMPs with only a slight variation among their members, possibly to increase their spectrum of activity. Despite the growing body of knowledge about their biological activity and mode of action on bacteria, only a few of them have been tested on Leishmania, a worldwide spread protozoan pathogen, and the parameters contributing to this activity are yet to be determined. We report on the anti-Leishmania activity and mode of action of bombinins H2 and H4 isolated from the skin secretion of the frog Bombina variegata. H4, the most active, is the first natural AMP of animal origin with a single L- to D-amino acid isomerization. Membrane depolarization and membrane permeation assays, as well as electron microscopy, suggest that the lethal mechanism involves plasma membrane permeation and/or disruption. To better understand the enhanced activity of H4, we determined the peptide's structure in membranes mimicking those of mammals, bacteria, and Leishmania by using ATR-FTIR and CD spectroscopies and assessed their membrane binding by using surface plasmon resonance. The data reveal that (i) H2 but not H4 partially aggregates in membranes mimicking those of Leishmania, (ii) H2 is slightly more helical than H4 in all membranes, and (iii) H4 binds the Leishmania model membrane approximately 5-fold better than H2. This study highlights the importance of a single alpha-amino acid epimerization as a tool used by nature to modulate the activity of AMPs. In addition, our findings suggest bombinins H as potential templates for the development of new drugs with a new mode of action against Leishmania.
Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche A. Rossi Fanelli, Azienda Ospedaliera S. Andrea, Università La Sapienza, Piazzale Aldo Moro 5, 00185 Rome, Italy. marialuisa.mangoni@uniroma1.it
Maria Luisa
ML
Mangoni
Niv
N
Papo
José M
JM
Saugar
Donatella
D
Barra
Yechiel
Y
Shai
Maurizio
M
Simmaco
Luis
L
Rivas
D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D000981:Antiprotozoal Agents / Q000494:pharmacology*; D001001:Anura; D002463:Cell Membrane Permeability / Q000187:drug effects; D002942:Circular Dichroism; D007893:Leishmania donovani / Q000187:drug effects / Q000648:ultrastructure; D008051:Lipid Bilayers / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D046529:Microscopy, Electron, Transmission; D009930:Organic Chemicals / Q000493:pharmacokinetics; D010455:Peptides; D017550:Spectroscopy, Fourier Transform Infrared; D013237:Stereoisomerism; D020349:Surface Plasmon Resonance
D023181:Antimicrobial Cationic Peptides; D000981:Antiprotozoal Agents; D008051:Lipid Bilayers; D009930:Organic Chemicals; D010455:Peptides; C402795:SYTOX Green; C510197:bombinin H2; C113470:gene-drived bombinin H-like peptide