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Chiral supramolecular architecture of stable transmembrane pores formed by an ?-helical antibiotic peptide in the presence of lyso-lipids.

ABSTRACT: The amphipathic ?-helical antimicrobial peptide MSI-103 (aka KIA21) can form stable transmembrane pores when the bilayer takes on a positive spontaneous curvature, e.g. by the addition of lyso-lipids. Solid-state 31P- and 15N-NMR demonstrated an enrichment of lyso-lipids in these toroidal wormholes. Anionic lyso-lipids provided additional stabilization by electrostatic interactions with the cationic peptides. The remaining lipid matrix did not affect the nature of the pore, as peptides maintained the same orientation independent of lipid charge, and a change in membrane thickness did not considerably affect their tilt angle. Under optimized conditions (i.e. in the presence of lyso-lipids and appropriate bilayer thickness), stable and well-aligned pores could be obtained for solid-state 2H-NMR analysis. These data revealed for the first time the complete 3D alignment of this representative amphiphilic peptide in fluid membranes, which is compatible with either monomeric helices as constituents, or left-handed supercoiled dimers as building blocks from which the overall toroidal wormhole is assembled.

SUBMITTER: Strandberg E

PROVIDER: S-EPMC7070102 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Chiral supramolecular architecture of stable transmembrane pores formed by an α-helical antibiotic peptide in the presence of lyso-lipids.

Strandberg Erik E Bentz David D Wadhwani Parvesh P Ulrich Anne S AS

Scientific reports 20200313 1

The amphipathic α-helical antimicrobial peptide MSI-103 (aka KIA21) can form stable transmembrane pores when the bilayer takes on a positive spontaneous curvature, e.g. by the addition of lyso-lipids. Solid-state <sup>31</sup>P- and <sup>15</sup>N-NMR demonstrated an enrichment of lyso-lipids in these toroidal wormholes. Anionic lyso-lipids provided additional stabilization by electrostatic interactions with the cationic peptides. The remaining lipid matrix did not affect the nature of the pore, ...[more]

PMID: 32170095

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Project description:We report kinetically controlled chiral supramolecular polymerization based on ligand-metal complex with a 3 : 2 (L : Ag+) stoichiometry accompanying a helical inversion in water. A new family of bipyridine-based ligands (d-L1, l-L1, d-L2, and d-L3) possessing hydrazine and d- or l-alanine moieties at the alkyl chain groups has been designed and synthesized. Interestingly, upon addition of AgNO3 (0.5-1.3 equiv.) to the d-L1 solution, it generated the aggregate I composed of the d-L1AgNO3 complex (d-L1 : Ag+ = 1 : 1) as the kinetic product with a spherical structure. Then, aggregate I (nanoparticle) was transformed into the aggregate II (supramolecular polymer) based on the (d-L1)3Ag2(NO3)2 complex as the thermodynamic product with a fiber structure, which led to the helical inversion from the left-handed (M-type) to the right-handed (P-type) helicity accompanying CD amplification. In contrast, the spherical aggregate I (nanoparticle) composed of the d-L1AgNO3 complex with the left-handed (M-type) helicity formed in the presence of 2.0 equiv. of AgNO3 and was not additionally changed, which indicated that it was the thermodynamic product. The chiral supramolecular polymer based on (d-L1)3Ag2(NO3)2 was produced via a nucleation-elongation mechanism with a cooperative pathway. In thermodynamic study, the standard ΔG° and ΔH e values for the aggregates I and II were calculated using the van't Hoff plot. The enhanced ΔG° value of the aggregate II compared to that of the formation of aggregate I confirms that aggregate II was thermodynamically more stable. In the kinetic study, the influence of concentration of AgNO3 confirmed the initial formation of the aggregate I (nanoparticle), which then evolved to the aggregate II (supramolecular polymer). Thus, the concentration of the (d-L1)3Ag2(NO3)2 complex in the initial state plays a critical role in generating aggregate II (supramolecular polymer). In particular, NO3 - acts as a critical linker and accelerator in the transformation from the aggregate I to the aggregate II. This is the first example of a system for a kinetically controlled chiral supramolecular polymer that is formed via multiple steps with coordination structural change.

Dataset Information

Chiral supramolecular architecture of stable transmembrane pores formed by an ?-helical antibiotic peptide in the presence of lyso-lipids.

Publications

Chiral supramolecular architecture of stable transmembrane pores formed by an α-helical antibiotic peptide in the presence of lyso-lipids.

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