Department of Biomedical Sciences, College of Veterinary Medicine, Corvallis, OR, USA.
Department of Microbiology, College of Science, Corvallis, OR, USA.
Sci Rep. 2017 Aug 1;7(1):7007. doi: 10.1038/s41598-017-06700-3.
Mycobacterium avium subsp. hominissuis is associated with infection of immunocompromised individuals as well as patients with chronic lung disease. M. avium infects macrophages and actively interfere with the host killing machinery such as apoptosis and autophagy. Bacteria alter the normal endosomal trafficking, prevent the maturation of phagosomes and modify many signaling pathways inside of the macrophage by secreting effector molecules into the cytoplasm. To investigate whether M. avium needs to attach to the internal surface of the vacuole membrane before releasing efferent molecules, vacuole membrane proteins were purified and binding to the surface molecules present in intracellular bacteria was evaluated. The voltage-dependent anion channels (VDAC) were identified as components of M. avium vacuoles in macrophages. M. avium mmpL4 proteins were found to bind to VDAC-1 protein. The inactivation of VDAC-1 function either by pharmacological means or siRNA lead to significant decrease of M. avium survival. Although, we could not establish a role of VDAC channels in the transport of known secreted M. avium proteins, we demonstrated that the porin channels are associated with the export of bacterial cell wall lipids outside of vacuole. Suppression of the host phagosomal transport systems and the pathogen transporter may serve as therapeutic targets for infectious diseases.
鸟分枝杆菌亚种同源感染与免疫功能低下个体以及慢性肺部疾病患者的感染有关。鸟分枝杆菌感染巨噬细胞,并通过主动干扰细胞凋亡和自噬等宿主杀伤机制来进行感染。细菌改变正常的内体运输,阻止吞噬体的成熟,并通过将效应分子分泌到细胞质中来修饰巨噬细胞内的许多信号通路。为了研究分枝杆菌在释放外排分子之前是否需要附着在空泡膜的内表面,纯化了空泡膜蛋白并评估了与细胞内细菌表面分子的结合。发现电压依赖性阴离子通道(VDAC)是巨噬细胞中分枝杆菌空泡的组成部分。发现分枝杆菌 mmpL4 蛋白与 VDAC-1 蛋白结合。通过药理学手段或 siRNA 使 VDAC-1 功能失活会导致分枝杆菌的存活率显著降低。尽管我们不能确定 VDAC 通道在已知分泌的分枝杆菌蛋白的运输中的作用,但我们证明了孔蛋白通道与细胞壁脂质从空泡中输出有关。抑制宿主吞噬体运输系统和病原体转运体可能是治疗感染性疾病的靶点。