Division of Infectious Diseases, Departments of Medicine and Microbiology and Immunology, University of British Columbia, Life Sciences Institute, Vancouver, British Columbia, V6T-1Z3, Canada.
Sci Rep. 2018 Jan 9;8(1):155. doi: 10.1038/s41598-017-18547-9.
Protein phosphorylation plays a key role in Mycobacterium tuberculosis (Mtb) physiology and pathogenesis. We have previously shown that a secreted protein tyrosine phosphatase, PtpA, is essential for Mtb inhibition of host macrophage acidification and maturation, and is a substrate of the protein tyrosine kinase, PtkA, encoded in the same operon. In this study, we constructed a ∆ptkA deletion mutant in Mtb and found that the mutant exhibited impaired intracellular survival in the THP-1 macrophage infection model, correlated with the strain's inability to inhibit macrophage phagosome acidification. By contrast, the mutant displayed increased resistance to oxidative stress in vitro. Proteomic and transcriptional analyses revealed upregulation of ptpA, and increased secretion of TrxB2, in the ΔptkA mutant. Kinase and protein-protein interaction studies demonstrated that TrxB2 is a substrate of PtkA phosphorylation. Taken together these studies establish a central role for the ptkA-ptpA operon in Mtb pathogenesis.
蛋白磷酸化在结核分枝杆菌（Mtb）的生理和发病机制中起着关键作用。我们之前已经表明，一种分泌的蛋白酪氨酸磷酸酶 PtpA 对于 Mtb 抑制宿主巨噬细胞酸化和成熟是必需的，并且是与同一操纵子中编码的蛋白酪氨酸激酶 PtkA 的底物。在这项研究中，我们构建了 Mtb 中的 ∆ptkA 缺失突变体，发现该突变体在 THP-1 巨噬细胞感染模型中的细胞内存活能力受损，与该菌株无法抑制巨噬细胞吞噬体酸化有关。相比之下，该突变体在体外显示出对氧化应激的抵抗力增加。蛋白质组学和转录分析显示，ΔptkA 突变体中 ptpA 的表达上调，以及 TrxB2 的分泌增加。激酶和蛋白质-蛋白质相互作用研究表明，TrxB2 是 PtkA 磷酸化的底物。综上所述，这些研究确立了 ptkA-ptpA 操纵子在 Mtb 发病机制中的核心作用。
