Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland; 1(st) Department of Internal Medicine, University of Cologne, 50937 Cologne, Germany.
Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
Cell Host Microbe. 2014 Oct 8;16(4):538-48. doi: 10.1016/j.chom.2014.09.008.
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.
结核分枝杆菌 (Mtb) 需要 ESX-1 等蛋白分泌系统来实现细胞内生存和毒力。主要的毒力决定因子和 ESX-1 底物 EsxA 会阻止吞噬体成熟并溶解细胞膜，导致组织损伤和坏死，从而促进病原体的传播。为了鉴定 Mtb 蛋白分泌的抑制剂，我们开发了一种利用这种表型的成纤维细胞存活测定法，并选择了可保护宿主细胞免受 Mtb 诱导的裂解而在体外无杀菌作用的分子。命中化合物可阻止 EsxA 分泌并促进巨噬细胞中的吞噬体成熟，从而降低细菌负荷。靶标鉴定研究发现了 BTP15，这是一种组氨酸激酶 MprB 的苯并噻吩抑制剂，它间接调节 ESX-1，以及 BBH7，一种苯氧基苄基腙化合物。BBH7 影响 Mtb 的金属离子动态平衡，并揭示锌应激是 EsxA 分泌的激活信号。这种筛选方法扩展了小分子文库的靶标范围，并将有助于解决日益严重的耐抗生素分枝杆菌问题。
