Faculty of Medicine, Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland.
Faculty of Science, Department of Biochemistry, University of Geneva, Geneva, Switzerland.
Cell Microbiol. 2019 Jun;21(6):e13008. doi: 10.1111/cmi.13008. Epub 2019 Feb 7.
The causative agent of tuberculosis, Mycobacterium tuberculosis, and its close relative Mycobacterium marinum manipulate phagocytic host cells, thereby creating a replication-permissive compartment termed the Mycobacterium-containing vacuole (MCV). The phosphoinositide (PI) lipid pattern is a crucial determinant of MCV formation and is targeted by mycobacterial PI phosphatases. In this study, we establish an efficient phage transduction protocol to construct defined M. marinum deletion mutants lacking one or three phosphatases, PtpA, PtpB, and/or SapM. These strains were defective for intracellular replication in macrophages and amoebae, and the growth defect was complemented by the corresponding plasmid-borne genes. Fluorescence microscopy of M. marinum-infected Dictyostelium discoideum revealed that MCVs harbouring mycobacteria lacking PtpA, SapM, or all three phosphatases accumulate significantly more phosphatidylinositol-3-phosphate (PtdIns3P) compared with MCVs containing the parental strain. Moreover, PtpA reduced MCV acidification by blocking the recruitment of the V-ATPase, and all three phosphatases promoted bacterial escape from the pathogen vacuole to the cytoplasm. In summary, the secreted M. marinum phosphatases PtpA, PtpB, and SapM determine the MCV PI pattern, compartment acidification, and phagosomal escape.
结核分枝杆菌(Mycobacterium tuberculosis)及其近亲海分枝杆菌(Mycobacterium marinum)是导致结核病的病原体,它们能够操纵吞噬宿主细胞,从而形成一个允许复制的隔室,称为分枝杆菌包含的空泡(Mycobacterium-containing vacuole,MCV)。磷酸肌醇(phosphoinositide,PI)脂质模式是 MCV 形成的关键决定因素,也是分枝杆菌 PI 磷酸酶的靶向目标。在本研究中,我们建立了一种有效的噬菌体转导方案,以构建缺失一种或三种磷酸酶(PtpA、PtpB 和/或 SapM)的特定 M. marinum 缺失突变株。这些菌株在巨噬细胞和变形虫中均不能进行有效的细胞内复制,而相应的质粒携带基因可弥补其生长缺陷。荧光显微镜观察表明,与野生型菌株相比,缺乏 PtpA、SapM 或三种磷酸酶的 MCV 中含有更多的磷脂酰肌醇-3-磷酸(phosphatidylinositol-3-phosphate,PtdIns3P)。此外,PtpA 通过阻断 V-ATPase 的募集来抑制 MCV 的酸化,而三种磷酸酶均促进细菌从病原体空泡逃逸到细胞质。综上所述,分泌的 M. marinum 磷酸酶 PtpA、PtpB 和 SapM 决定了 MCV 的 PI 模式、隔室酸化和吞噬体逃逸。