Studies on the interaction of alyteserin 1c peptideand its cationic analogue with model membranes imitating mammalian and bacterial membranes
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Date
2019-09-25
Journal Title
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Publisher
MDPI AG
Abstract
Antimicrobial peptides (AMPs) are effector molecules of the innate immune system and
have been isolated from multiple organisms. Their antimicrobial properties are due to the fact that they
interact mainly with the anionic membrane of the microorganisms, permeabilizing it and releasing the
cytoplasmic content. Alyteserin 1c (+2), an AMP isolated from Alytes obstetricans and its more cationic
and hydrophilic analogue (+5) were synthesized using the solid phase method, in order to study the
interaction with model membranes by calorimetric and spectroscopic assays. Differential scanning
calorimetry (DSC) showed that both peptides had a strong effect when the membrane contained
phosphatidylcholine (PC) alone or was mixed with phosphatidylglycerol (PG), increasing membrane
fluidization. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was used
to study the secondary structure of the peptide. Peptide +2 exhibited a transition from β-sheet/turns to
β-sheet/α-helix structures after binding with model membranes, whereas peptide +5 had a transition
from aggregation/unordered to β-sheet/α-helix structures after binding with membrane-contained
PC. Interestingly, the latter showed a β-sheet structure predominantly in the presence of PG lipids.
Additionally, molecular dynamics (MD) results showed that the carboxy-terminal of the peptide
+5 has the ability to insert into the surface of the PC/PG membranes, resulting in the increase of the
membrane fluidity
Description
Keywords
Alyteserin 1c, Model membranes, Calorimetry, Infrared spectroscopy, Molecular dynamics