Daptomycin, a last-resort antibiotic, binds ribosomal protein S19 in humans.

Ho Jeong Kwon,Peter Karuso,Michael P. Gotsbacher,Sungmin Cho

doi:10.1186/s12953-017-0124-2

Abstract

BackgroundDaptomycin is a recently introduced, last-resort antibiotic that displays a unique mode of action against Gram-positive bacteria that is not fully understood. Several bacterial targets have been proposed but no human binding partner is known.MethodsIn the present study we tested daptomycin in cell viability and proliferation assays against six human cell lines, describe the synthesis of biotinylated and fluorescently labeled analogues of daptomycin. Biotinylated daptomycin was used as bait to isolate the human binding partner by the application of reverse chemical proteomics using T7 phage display of five human tumor cDNA libraries. The interaction between the rescued protein and daptomycin was validated via siRNA knockdown, DARTS assay and immunocytochemistry.ResultsWe have found that daptomycin possesses selective growth inhibition of some cancer cell lines, especially MCF7. The unbiased interrogation of human cDNA libraries, displayed on bacteriophage T7, revealed a single human target of daptomycin; ribosomal protein S19. Using a drug affinity responsive target stability (DARTS) assay in vitro, we show that daptomycin stabilizes RPS19 toward pronase. Fluorescently labeled daptomycin stained specific structures in HeLa cells and co-localized with a RPS19 antibody.ConclusionThis study provides, for the first time, a human protein target of daptomycin and identifies RPS19 as a possible anticancer drug target for the development of new pharmacological applications and research.Electronic supplementary materialThe online version of this article (doi:10.1186/s12953-017-0124-2) contains supplementary material, which is available to authorized users.

Highlights

Daptomycin is a recently introduced, last-resort antibiotic that displays a unique mode of action against Gram-positive bacteria that is not fully understood
It was first approved by the Food and Drug Administration (FDA) for non-topical use in 2003 for the treatment of skin infections caused by Gram-positive bacteria, and in 2006
Biological activity of DAP in human cell lines DAP was bioassayed against six human cell lines, up to 80 μM for 3 days (Table 1; Additional file 1: Figure S9)

Summary

Introduction

Daptomycin is a recently introduced, last-resort antibiotic that displays a unique mode of action against Gram-positive bacteria that is not fully understood. DAP has recently been introduced as a last-resort antibiotic with excellent activity against Gram-positive pathogens. It was first approved by the Food and Drug Administration (FDA) for non-topical use in 2003 for the treatment of skin infections caused by Gram-positive bacteria, and in 2006. Bound antibiotic could be removed by washing with EDTA It was observed in phospholipid bilayer studies that DAP induces, in a Ca2+ dependent manner, substantial lipid flip-flop [5]. This phenomenon is potentially relevant for DAP's entry into human cells, but it is unknown what it interacts with in the lipid bilayer or the cytoplasm

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Conclusion