title: Anticytolytic screen identifies inhibitors of mycobacterial virulence protein secretion.
abstract: Mycobacterium tuberculosis (Mtb) requires protein secretion systems like ESX-1 for intracellular survival and virulence. The major virulence determinant and ESX-1 substrate, EsxA, arrests phagosome maturation and lyses cell membranes, resulting in tissue damage and necrosis that promotes pathogen spread. To identify inhibitors of Mtb protein secretion, we developed a fibroblast survival assay exploiting this phenotype and selected molecules that protect host cells from Mtb-induced lysis without being bactericidal in vitro. Hit compounds blocked EsxA secretion and promoted phagosome maturation in macrophages, thus reducing bacterial loads. Target identification studies led to the discovery of BTP15, a benzothiophene inhibitor of the histidine kinase MprB that indirectly regulates ESX-1, and BBH7, a benzyloxybenzylidene-hydrazine compound. BBH7 affects Mtb metal-ion homeostasis and revealed zinc stress as an activating signal for EsxA secretion. This screening approach extends the target spectrum of small molecule libraries and will help tackle the mounting problem of antibiotic-resistant mycobacteria.
authors.affiliation: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland; 1(st) Department of Internal Medicine, University of Cologne, 50937 Cologne, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Rybniker
authors.affiliation: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Chen
authors.affiliation: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Claudia
authors.initials: C
authors.lastname: Sala
authors.affiliation: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Ruben C
authors.initials: RC
authors.lastname: Hartkoorn
authors.affiliation: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Anthony
authors.initials: A
authors.lastname: Vocat
authors.affiliation: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Andrej
authors.initials: A
authors.lastname: Benjak
authors.affiliation: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Boy-Röttger
authors.affiliation: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Ming
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Rita
authors.initials: R
authors.lastname: Székely
authors.affiliation: Vichem Chemie Research Ltd., Herman Otto u. 15, 1022 Budapest, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Greff
authors.affiliation: Vichem Chemie Research Ltd., Herman Otto u. 15, 1022 Budapest, Hungary; Department of Pharmaceutical Chemistry, Semmelweis University, Hőgyes Endre u. 9, 1092 Budapest, Hungary.
authors.forename: László
authors.initials: L
authors.lastname: Orfi
authors.affiliation: Vichem Chemie Research Ltd., Herman Otto u. 15, 1022 Budapest, Hungary.
authors.forename: István
authors.initials: I
authors.lastname: Szabadkai
authors.affiliation: Vichem Chemie Research Ltd., Herman Otto u. 15, 1022 Budapest, Hungary.
authors.forename: János
authors.initials: J
authors.lastname: Pató
authors.affiliation: Vichem Chemie Research Ltd., Herman Otto u. 15, 1022 Budapest, Hungary; MTA-SE Pathobiochemistry Research Group, Department of Medical Chemistry, Semmelweis University, 1094 Budapest, Hungary.
authors.forename: György
authors.initials: G
authors.lastname: Kéri
authors.affiliation: Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland. Electronic address: stewart.cole@epfl.ch.
authors.forename: Stewart T
authors.initials: ST
authors.lastname: Cole
mesh_terms: D000900:Anti-Bacterial Agents / Q000302:isolation & purification* / Q000494:pharmacology; D000942:Antigens, Bacterial; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors*; D002470:Cell Survival; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D005347:Fibroblasts / Q000382:microbiology / Q000502:physiology*; D020869:Gene Expression Profiling; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D037521:Virulence Factors / Q000037:antagonists & inhibitors*
chemical_list: D000900:Anti-Bacterial Agents; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D037521:Virulence Factors