TY - JOUR
T1 - Divorcing folding from function: how acylation affects the membrane-perturbing properties of an antimicrobial peptide
AU - Vad, Brian Stougaard
AU - Thomsen, Line Aagot Hede
AU - Bertelsen, Kresten
AU - Franzmann, Magnus
AU - Pedersen, Jan Mondrup
AU - Nielsen, Søren Bang
AU - Vosegaard, Thomas
AU - Valnickova, Zuzana
AU - Skrydstrup, Troels
AU - Enghild, Jan J.
AU - Wimmer, Reinhard
AU - Nielsen, Niels Christian
AU - Otzen, Daniel
N1 - Copyright 2009 Elsevier B.V. All rights reserved.
PY - 2010
Y1 - 2010
N2 - Many small cationic peptides, which are unstructured in aqueous solution, have antimicrobial properties. These properties are assumed to be linked to their ability to permeabilize bacterial membranes, accompanied by the transition to an alpha-helical folding state. Here we show that there is no direct link between folding of the antimicrobial peptide Novicidin (Nc) and its membrane permeabilization. N-terminal acylation with C8-C16 alkyl chains and the inclusion of anionic lipids both increase Nc's ability to form alpha-helical structure in the presence of vesicles. Nevertheless, both acylation and anionic lipids reduce the extent of permeabilization of these vesicles and lead to slower permeabilization kinetics. Furthermore, acylation significantly decreases antimicrobial activity. Although acyl chains of increasing length also increase the tendency of the peptides to aggregate in solution, this cannot rationalize our results since permeabilization and antimicrobial activities are observed well below concentrations where aggregation occurs. This suggests that significant induction of alpha-helical structure is not a prerequisite for membrane perturbation in this class of antimicrobial peptides. Our data suggests that for Nc, induction of alpha-helical structure may inhibit rather than facilitate membrane disruption, and that a more peripheral interaction may be the most efficient permeabilization mechanism. Furthermore, acylation leads to a deeper embedding in the membrane, which could lead to an anti-permeabilizing "plugging" effect.
AB - Many small cationic peptides, which are unstructured in aqueous solution, have antimicrobial properties. These properties are assumed to be linked to their ability to permeabilize bacterial membranes, accompanied by the transition to an alpha-helical folding state. Here we show that there is no direct link between folding of the antimicrobial peptide Novicidin (Nc) and its membrane permeabilization. N-terminal acylation with C8-C16 alkyl chains and the inclusion of anionic lipids both increase Nc's ability to form alpha-helical structure in the presence of vesicles. Nevertheless, both acylation and anionic lipids reduce the extent of permeabilization of these vesicles and lead to slower permeabilization kinetics. Furthermore, acylation significantly decreases antimicrobial activity. Although acyl chains of increasing length also increase the tendency of the peptides to aggregate in solution, this cannot rationalize our results since permeabilization and antimicrobial activities are observed well below concentrations where aggregation occurs. This suggests that significant induction of alpha-helical structure is not a prerequisite for membrane perturbation in this class of antimicrobial peptides. Our data suggests that for Nc, induction of alpha-helical structure may inhibit rather than facilitate membrane disruption, and that a more peripheral interaction may be the most efficient permeabilization mechanism. Furthermore, acylation leads to a deeper embedding in the membrane, which could lead to an anti-permeabilizing "plugging" effect.
KW - Acylation
KW - Amino Acid Sequence
KW - Antimicrobial Cationic Peptides
KW - Cell Membrane Permeability
KW - Escherichia coli
KW - Fluorescence Polarization
KW - Liposomes
KW - Membrane Lipids
KW - Micelles
KW - Models, Molecular
KW - Molecular Sequence Data
KW - Nuclear Magnetic Resonance, Biomolecular
KW - Phase Transition
KW - Protein Folding
KW - Protein Multimerization
KW - Protein Structure, Secondary
U2 - 10.1016/j.bbapap.2009.12.006
DO - 10.1016/j.bbapap.2009.12.006
M3 - Journal article
C2 - 20026432
SN - 1570-9639
VL - 1804
SP - 806
EP - 820
JO - B B A - Proteins and Proteomics
JF - B B A - Proteins and Proteomics
IS - 4
ER -