Daptomycin inhibits cell envelope synthesis by interfering with fluid membrane microdomains

Anna Müller, Michaela Wenzel, Henrik Strahl, Fabian Grein, Terrens N.V. Saaki, Bastian Kohl, Tjalling Siersma, Julia E. Bandow, Hans Georg Sahl, Tanja Schneider, Leendert W. Hamoen*

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Daptomycin is a highly efficient last-resort antibiotic that targets the bacterial cell membrane. Despite its clinical importance, the exact mechanism by which daptomycin kills bacteria is not fully understood. Different experiments have led to different models, including (i) blockage of cell wall synthesis, (ii) membrane pore formation, and (iii) the generation of altered membrane curvature leading to aberrant recruitment of proteins. To determine which model is correct, we carried out a comprehensive mode-of-action study using the model organism Bacillus subtilis and different assays, including proteomics, ionomics, and fluorescence light microscopy. We found that daptomycin causes a gradual decrease in membrane potential but does not form discrete membrane pores. Although we found no evidence for altered membrane curvature, we confirmed that daptomycin inhibits cell wall synthesis. Interestingly, using different fluorescent lipid probes, we showed that binding of daptomycin led to a drastic rearrangement of fluid lipid domains, affecting overall membrane fluidity. Importantly, these changes resulted in the rapid detachment of themembrane-associated lipid II synthase MurG and the phospholipid synthase PlsX. Both proteins preferentially colocalize with fluid membrane microdomains. Delocalization of these proteins presumably is a key reason why daptomycin blocks cell wall synthesis. Finally, clustering of fluid lipids by daptomycin likely causes hydrophobic mismatches between fluid and more rigid membrane areas. This mismatch can facilitate proton leakage and may explain the gradual membrane depolarization observed with daptomycin. Targeting of fluid lipid domains has not been described before for antibiotics and adds another dimension to our understanding of membrane-active antibiotics.

Original languageEnglish
Pages (from-to)E7077-E7086
JournalProceedings of the National Academy of Sciences of the United States of America
Volume113
Issue number45
DOIs
Publication statusPublished - 8 Nov 2016
Externally publishedYes

Keywords

  • Antibiotics
  • Bacillus subtilis
  • Cell wall biosynthesis
  • Daptomycin
  • Membrane potential

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