Ca2+-Daptomycin targets cell wall biosynthesis by forming a tripartite complex with undecaprenyl-coupled intermediates and membrane lipids

Fabian Grein,Hans-Georg Sahl,Anna Klöckner,Katharina M Scherer,Xinliang Liu,Manuel Strach,Anna Müller,Tanja Schneider,Ulrich Kubitscheck,Kevin C Ludwig

doi:10.1038/s41467-020-15257-1

Abstract

The lipopeptide daptomycin is used as an antibiotic to treat severe infections with gram-positive pathogens, such as methicillin resistant Staphylococcus aureus (MRSA) and drug-resistant enterococci. Its precise mechanism of action is incompletely understood, and a specific molecular target has not been identified. Here we show that Ca2+-daptomycin specifically interacts with undecaprenyl-coupled cell envelope precursors in the presence of the anionic phospholipid phosphatidylglycerol, forming a tripartite complex. We use microbiological and biochemical assays, in combination with fluorescence and optical sectioning microscopy of intact staphylococcal cells and model membrane systems. Binding primarily occurs at the staphylococcal septum and interrupts cell wall biosynthesis. This is followed by delocalisation of components of the peptidoglycan biosynthesis machinery and massive membrane rearrangements, which may account for the pleiotropic cellular events previously reported. The identification of carrier-bound cell wall precursors as specific targets explains the specificity of daptomycin for bacterial cells. Our work reconciles apparently inconsistent previous results, and supports a concise model for the mode of action of daptomycin.

Highlights

The lipopeptide daptomycin is used as an antibiotic to treat severe infections with grampositive pathogens, such as methicillin resistant Staphylococcus aureus (MRSA) and drugresistant enterococci
Being initially considered unsuitable for clinical application due to toxic myopathies, a revised once-daily administration scheme was approved by the US Food and Drug Administration (FDA) in 2003 for the treatment of complicated skin and soft-tissue infections caused by various Gram-positive pathogens, making it the first lipopeptide antibiotic in clinical use
The complex formation with Ca2+ affects the physicochemical properties of DAP, masking the anionic nature and conferring an overall amphiphilic character. Since this is a typical feature of cationic antimicrobial peptides it was suggested that DAP likewise would act as cAMPs, which primarily target negatively charged microbial membranes[5]

Summary

Introduction

The lipopeptide daptomycin is used as an antibiotic to treat severe infections with grampositive pathogens, such as methicillin resistant Staphylococcus aureus (MRSA) and drugresistant enterococci. The complex formation with Ca2+ affects the physicochemical properties of DAP, masking the anionic nature and conferring an overall amphiphilic character Since this is a typical feature of cationic antimicrobial peptides (cAMPs) it was suggested that DAP likewise would act as cAMPs, which primarily target negatively charged microbial membranes[5]. One model, originating from structural studies and the observed membrane depolarising effect, suggests that Ca2+-DAP forms oligomeric aggregates, which upon contact with phosphatidylglycerol (PG) rearrange into a pore-like complex, leading to ion leakage and dissipation of membrane potential[5]. The second model suggests that DAP insertion at specific membrane domains, enriched in PG, affects the physicochemical properties of the cytoplasmic membrane, triggering pleiotropic effects on essential cell wall biosynthesis and cell division processes[9,12]

Methods

Results

Conclusion