Membrane structure and conformational changes of the antibiotic heterodimeric peptide distinctin by solid-state NMR spectroscopy.
The heterodimeric antimicrobial peptide distinctin is composed of 2 linear peptide chains of 22- and 25-aa residues that are connected by a single intermolecular S-S bond. This heterodimer has been considered to be a unique example of a previously unrecorded class of bioactive peptides. Here the 2 distinctin chains were prepared by chemical peptide synthesis in quantitative amounts and labeled with (15)N, as well as (15)N and (2)H, at selected residues, respectively, and the heterodimer was formed by oxidation. CD spectroscopy indicates a high content of helical secondary structures when associated with POPC/POPG 3:1 vesicles or in membrane-mimetic environments. The propensity for helix formation follows the order heterodimer >chain 2 >chain 1, suggesting that peptide-peptide and peptide-lipid interactions both help in stabilizing this secondary structure. In a subsequent step the peptides were reconstituted into oriented phospholipid bilayers and investigated by (2)H and proton-decoupled (15)N solid-state NMR spectroscopy. Whereas chain 2 stably inserts into the membrane at orientations close to perfectly parallel to the membrane surface in the presence or absence of chain 1, the latter adopts a more tilted alignment, which further increases in the heterodimer. The data suggest that membrane interactions result in considerable conformational rearrangements of the heterodimer. Therefore, chain 2 stably anchors the heterodimer in the membrane, whereas chain 1 interacts more loosely with the bilayer. These structural observations are consistent with the antimicrobial activities when the individual chains are compared to the dimer.
Resende
Jarbas M
JM
Université de Strasbourg, Centre National de la Recherche Scientifique, UMR 7177, Institut de Chimie, 4 rue Blaise Pascal, Strasbourg, France.
Moraes
Cléria Mendonça
CM
Munhoz
Victor H O
VH
Aisenbrey
Christopher
C
Verly
Rodrigo M
RM
Bertani
Philippe
P
Cesar
Amary
A
Piló-Veloso
Dorila
D
Bechinger
Burkhard
B
D029845:Amphibian Proteins / Q000737:chemistry*; D000890:Anti-Infective Agents / Q000737:chemistry*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry*; D002942:Circular Dichroism; D008565:Membrane Proteins / Q000737:chemistry*; D008954:Models, Biological; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction; D011487:Protein Conformation
D029845:Amphibian Proteins; D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D008565:Membrane Proteins; C531945:distinctin