Cardiolipin Prevents Membrane Translocation and Permeabilization by Daptomycin

• Published in: The Journal of biological chemistry 2014-04, Vol.289 (17), p.11584-11591
• Main Authors: Zhang, TianHua, Muraih, Jawad K., Tishbi, Nasim, Herskowitz, Jennifer, Victor, Rachel L., Silverman, Jared, Uwumarenogie, Stephanie, Taylor, Scott D., Palmer, Michael, Mintzer, Evan
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - pharmacology; Antibiotic Resistance; Antibiotics Action; Biological Transport - drug effects; Biological Transport - physiology; Calorimetry; Cardiolipin; Cardiolipins - physiology; Cell Membrane Permeability - drug effects; Daptomycin - pharmacology; Fluorescence; Gram-Positive Bacteria - drug effects; Isothermal Titration Calorimetry; Langmuir Monolayers; Lipopeptides; Liposomes; Membrane Biology; Phosphatidylglycerol
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M114.554444

Daptomycin is an acidic lipopeptide antibiotic that, in the presence of calcium, forms oligomeric pores on membranes containing phosphatidylglycerol. It is clinically used against various Gram-positive bacteria such as Staphylococcus aureus and Enterococcus species. Genetic studies have indicated that an increased content of cardiolipin in the bacterial membrane may contribute to bacterial resistance against the drug. Here, we used a liposome model to demonstrate that cardiolipin directly inhibits membrane permeabilization by daptomycin. When cardiolipin is added at molar fractions of 10 or 20% to membranes containing phosphatidylglycerol, daptomycin no longer forms pores or translocates to the inner membrane leaflet. Under the same conditions, daptomycin continues to form oligomers; however, these oligomers contain only close to four subunits, which is approximately half as many as observed on membranes without cardiolipin. The collective findings lead us to propose that a daptomycin pore consists of two aligned tetramers in opposite leaflets and that cardiolipin prevents the translocation of tetramers to the inner leaflet, thereby forestalling the formation of complete, octameric pores. Our findings suggest a possible mechanism by which cardiolipin may mediate resistance to daptomycin, and they provide new insights into the action mode of this important antibiotic. Daptomycin forms oligomeric pores in bacterial cell membranes. Cardiolipin is a membrane lipid associated with bacterial resistance to the antibiotic. Cardiolipin makes liposomes impervious to daptomycin permeabilization, and it confines daptomycin to the outer membrane leaflet. Preventing daptomycin from reaching the inner membrane leaflet inhibits pore formation. Bacteria may become resistant to daptomycin by changing their membrane lipid composition.