Curvature-Dependent Recognition of Ethanolamine Phospholipids by Duramycin and Cinnamycin

Supra-Biomolecular System Research Group, RIKEN (Institute of Physical and Chemical Research) Frontier Research System, Saitama, Japan.
Biophysical Journal (Impact Factor: 3.97). 10/2007; 93(5):1608-19. DOI: 10.1529/biophysj.106.101584
Source: PubMed


Duramycin is a 19-amino-acid tetracyclic lantibiotic closely related to cinnamycin (Ro09-0198), which is known to bind phosphatidylethanolamine (PE). The lipid specificity of duramycin was not established. The present study indicates that both duramycin and cinnamycin exclusively bind to ethanolamine phospholipids (PE and ethanolamine plasmalogen). Model membrane study indicates that the binding of duramycin and cinnamycin to PE-containing liposomes is dependent on membrane curvature, i.e., the lantibiotics bind small vesicles more efficiently than large liposomes. The binding of the lantibiotics to multilamellar liposomes induces tubulation of membranes, as revealed by electron microscopy and small-angle x-ray scattering. These results suggest that both duramycin and cinnamycin promote their binding to the PE-containing membrane by deforming membrane curvature.

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    • "Duramycin binds PE with a high affinity with a Kd reported at around 5 nM [12]. It was also reported that once bound to PE, the binding does not readily dissociate even in the presence of organic solvent [12]. A combination of tight binding with low molecular weight makes duramycin a candidate of interest for cardiovascular imaging applications. "
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    ABSTRACT: When pathologically externalized, phosphatidylethanolamine (PE) is a potential surrogate marker for detecting tissue injuries. 99mTc-labeled duramycin is a peptide-based imaging agent that binds PE with high affinity and specificity. The goal of the current study was to investigate the clearance kinetics of 99mTc-labeled duramycin in a large animal model (normal pigs) and to assess its uptake in the heart using a pig model of myocardial ischemia-reperfusion injury. Methods The clearance and distribution of intravenously injected 99mTc-duramycin were characterized in sham-operated animals (n = 5). In a closed chest model of myocardial ischemia, coronary occlusion was induced by balloon angioplasty (n = 9). 99mTc-duramycin (10–15 mCi) was injected intravenously at 1 hour after reperfusion. SPECT/CT was acquired at 1 and 3 hours after injection. Cardiac tissues were analyzed for changes associated with acute cellular injuries. Autoradiography and gamma counting was used to determine radioactivity uptake. For the remaining animals, 99mTc-tetrafosamin scan was performed on the second day to identify the infarct site. Results Intravenously injected 99mTc-duramycin cleared from circulation predominantly via the renal/urinary tract with an α-phase half-life of 3.6 ± 0.3 minutes and β-phase half-life of 179.9 ± 64.7 minutes. In control animals, the ratios between normal heart and lung were 1.76 ± 0.21, 1.66 ± 0.22, 1.50 ± 0.20 and 1.75 ± 0.31 at 0.5, 1, 2 and 3 hours post injection, respectively. The ratios between normal heart and liver were 0.88 ± 0.13, 0.80 ± 0.13, 0.82 ± 0.19 and 0.88 ± 0.14. In vivo visualization of focal radioactivity uptake in the ischemic heart was attainable as early as 30 min post injection. The in vivo ischemic-to-normal uptake ratios were 3.57 ± 0.74 and 3.69 ± 0.91 at 1 and 3 hours post injection, respectively. Ischemic-to-lung ratios were 4.89 ± 0.85 and 4.93 ± 0.57; and ischemic-to-liver ratios were 2.05 ± 0.30 to 3.23 ± 0.78. The size of 99mTc-duramycin positive myocardium was qualitatively larger than the infarct size delineated by the perfusion defect in 99mTc-tetrafosmin uptake. This was consistent with findings from tissue analysis and autoradiography. Conclusion 99mTc-duramycin was demonstrated, in a large animal model, to have suitable clearance and biodistribution profiles for imaging. The agent has an avid target uptake and a fast background clearance. It is appropriate for imaging myocardial injury induced by ischemia/reperfusion.
    Full-text · Article · Sep 2014 · Nuclear Medicine and Biology
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    • "Small unilamellar vesicles consisting of POPC and cholesterol (0–50 mol%) with or without 1 mol% of NBD-PE were prepared as described previously [28]. TNM-AMCA (1 µM) was mixed with small unilamellar vesicles (100 µM total lipids) in an incubation buffer (20 mM HEPES, pH 7.4, 100 mM NaCl), followed by 30 min incubation. "
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    ABSTRACT: Cholesterol plays important roles in biological membranes. The cellular location where cholesterol molecules work is prerequisite information for understanding their dynamic action. Bioimaging probes for cholesterol molecules would be the most powerful means for unraveling the complex nature of lipid membranes. However, only a limited number of chemical or protein probes have been developed so far for cytological analysis. Here we show that fluorescently-labeled derivatives of theonellamides act as new sterol probes in mammalian cultured cells. The fluorescent probes recognized cholesterol molecules and bound to liposomes in a cholesterol-concentration dependent manner. The probes showed patchy distribution in the plasma membrane, while they stained specific organelle in the cytoplasm. These data suggest that fTNMs will be valuable sterol probes for studies on the role of sterols in the biological membrane under a variety of experimental conditions.
    Full-text · Article · Dec 2013 · PLoS ONE
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    • "PE was detected using a small antibiotic peptide, duramycin (from Streptoverticillium cinnamoneus) belonging to a family of tetracyclic polypeptides. Peptides from this family have previously been used to detect PE on cell surfaces [22] [23]. "
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    ABSTRACT: The major anionic phospholipid, phosphatidylserine (PS), and the neutral phospholipid, phosphatidylethanolamine (PE), are largely confined to the inner leaflet of the plasma membrane bilayer in mammalian cells under normal conditions. This asymmetry is lost when cells undergo apoptosis, become activated, or are exposed to irradiation, reactive oxygen species or certain drugs. It is not known whether exposure of anionic phospholipids (APLs) and PE occurs simultaneously or in the same region of the plasma membrane. Here we examined the coincidence of exposure of APLs and PE on the surface of bovine aortic endothelial cells and NS0 myeloma cells after irradiation. The cells were irradiated (5 Gy) and stained for APLs and PE using liposomes coated with either an Fab′ fragment of a PS-binding antibody (bavituximab) or a PE-binding peptide (duramycin). Using live cell imaging and flow cytometry, we showed that irradiation leads to synchronous externalization of APLs and PE. The time course of appearance of APLs and PE on the cell surface was the same and the two phospholipid types remained colocalized over time. Distinct patches double positive for APLs and PE were visible. Larger areas of APLs and PE appeared to have detached from the cytoskeleton to form membrane blebs which protruded and drifted on the cell surface. We conclude that APLs and PE coincidently appear on the external leaflet of the plasma membrane of cells after irradiation. Probably, this is because PE and the major APL, PS, share common regulatory mechanisms of translocation.
    Preview · Article · Oct 2008 · Biochimica et Biophysica Acta
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