Sterol-dependent membrane association of the marine sponge-derived bicyclic peptide Theonellamide A as examined by1H NMR

Kimberly Cornelio, Rafael Atillo Espiritu, Yasuto Todokoro, Shinya Hanashima, Masanao Kinoshita, Nobuaki Matsumori, Michio Murata, Shinichi Nishimura, Hideaki Kakeya, Minoru Yoshida, Shigeki Matsunaga

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6 Citations (Scopus)


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, several1H 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 the1H NMR spectra of TNM-A with sodium dodecyl sulfate-d25(SDS-d25) micelles and small dimyristoylphosphatidylcholine (DMPC)-d54/dihexanoylphosphatidylcholine (DHPC)-d22bicelles 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, broader1H signals of TNM-A were observed in 10 mol % 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.

Original languageEnglish
Pages (from-to)5235-5242
Number of pages8
JournalBioorganic and Medicinal Chemistry
Issue number21
Publication statusPublished - 2016

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Medicine
  • Molecular Biology
  • Pharmaceutical Science
  • Drug Discovery
  • Clinical Biochemistry
  • Organic Chemistry


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