A folding-dependent mechanism of antimicrobial peptide resistance to degradation unveiled by solution structure of distinctin.
Many bioactive peptides, presenting an unstructured conformation in aqueous solution, are made resistant to degradation by posttranslational modifications. Here, we describe how molecular oligomerization in aqueous solution can generate a still unknown transport form for amphipathic peptides, which is more compact and resistant to proteases than forms related to any possible monomer. This phenomenon emerged from 3D structure, function, and degradation properties of distinctin, a heterodimeric antimicrobial compound consisting of two peptide chains linked by a disulfide bond. After homodimerization in water, this peptide exhibited a fold consisting of a symmetrical full-parallel four-helix bundle, with a well secluded hydrophobic core and exposed basic residues. This fold significantly stabilizes distinctin against proteases compared with other linear amphipathic peptides, without affecting its antimicrobial, hemolytic, and ion-channel formation properties after membrane interaction. This full-parallel helical orientation represents a perfect compromise between formation of a stable structure in water and requirement of a drastic structural rearrangement in membranes to elicit antimicrobial potential. Thus, distinctin can be claimed as a prototype of a previously unrecognized class of antimicrobial derivatives. These results suggest a critical revision of the role of peptide oligomerization whenever solubility or resistance to proteases is known to affect biological properties.
Raimondo
Domenico
D
Institute of Biomolecular Chemistry, National Research Council, Comprensorio Olivetti, Edificio 70, I-80078 Pozzuoli (Naples), Italy.
Andreotti
Giuseppina
G
Saint
Nathalie
N
Amodeo
Pietro
P
Renzone
Giovanni
G
Sanseverino
Marina
M
Zocchi
Ivana
I
Molle
Gerard
G
Motta
Andrea
A
Scaloni
Andrea
A
D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000378:metabolism*; D001001:Anura / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D019281:Dimerization; D007473:Ion Channels / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D010447:Peptide Hydrolases / Q000378:metabolism*; D011487:Protein Conformation; D017510:Protein Folding; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D014867:Water / Q000378:metabolism
D023181:Antimicrobial Cationic Peptides; D007473:Ion Channels; D014867:Water; D010447:Peptide Hydrolases