Sterol-dependent membrane association of the marine sponge-derived bicyclic peptide Theonellamide A as examined by 1H NMR
[Display omitted] Theonellamide A (TNM-A) is an antifungal bicyclic dodecapeptide isolated from a marine sponge Theonella sp. Previous studies have shown that TNM-A preferentially binds to 3β-hydroxysterol-containing membranes and disrupts membrane integrity. In this study, several 1H NMR-based expe...
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Published in | Bioorganic & medicinal chemistry Vol. 24; no. 21; pp. 5235 - 5242 |
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Main Authors | , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Elsevier Ltd
01.11.2016
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Subjects | |
Online Access | Get full text |
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Summary: | [Display omitted]
Theonellamide A (TNM-A) is an antifungal bicyclic dodecapeptide isolated from a marine sponge Theonella sp. Previous studies have shown that TNM-A preferentially binds to 3β-hydroxysterol-containing membranes and disrupts membrane integrity. In this study, several 1H NMR-based experiments were performed to investigate the interaction mode of TNM-A with model membranes. First, the aggregation propensities of TNM-A were examined using diffusion ordered spectroscopy; the results indicate that TNM-A tends to form oligomeric aggregates of 2–9 molecules (depending on peptide concentration) in an aqueous environment, and this aggregation potentially influences the membrane-disrupting activity of the peptide. Subsequently, we measured the 1H NMR spectra of TNM-A with sodium dodecyl sulfate-d25 (SDS-d25) micelles and small dimyristoylphosphatidylcholine (DMPC)-d54/dihexanoylphosphatidylcholine (DHPC)-d22 bicelles in the presence of a paramagnetic quencher Mn2+. These spectra indicate that TNM-A poorly binds to these membrane mimics without sterol and mostly remains in the aqueous media. In contrast, broader 1H signals of TNM-A were observed in 10mol% cholesterol-containing bicelles, indicating that the peptide efficiently binds to sterol-containing bilayers. The addition of Mn2+ to these bicelles also led to a decrease in the relative intensity and further line-broadening of TNM-A signals, indicating that the peptide stays near the surface of the bilayers. A comparison of the relative signal intensities with those of phospholipids showed that TNM-A resides in the lipid–water interface (close to the C2′ portion of the phospholipid acyl chain). This shallow penetration of TNM-A to lipid bilayers induces an uneven membrane curvature and eventually disrupts membrane integrity. These results shed light on the atomistic mechanism accounting for the membrane-disrupting activity of TNM-A and the important role of cholesterol in its mechanism of action. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0968-0896 1464-3391 |
DOI: | 10.1016/j.bmc.2016.08.043 |