The sensor kinase MtrB of Mycobacterium tuberculosis regulates hypoxic survival and establishment of infection
The sensor kinase MtrB of Mycobacterium tuberculosis regulates hypoxic survival and establishment of infection
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DOI：
10.1074/jbc.ra119.009449
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发表时间：
2019-12-27
影响因子：
4.8
通讯作者：
Kundu, Manikuntala
中科院分区：
文献类型：
--
作者：
Banerjee, Srijon;Lata, Suruchi;Kundu, Manikuntala
配对双组分系统（TCS）具有传感器激酶（SK）和同源反应调节器（RR），使人类病原体结核分枝杆菌能够对外部环境做出反应并在宿主体内持续存在。在这里，我们灭活了 TCS MtrAB、mtrB 的 SK 基因，产生菌株 ?mtrB。我们发现 mtrB 缺失会降低细菌在巨噬细胞中的生存能力，并增加其与自噬体和自溶酶体的关联。值得注意的是，?mtrB 菌株在小鼠肺部感染方面存在明显缺陷，在气溶胶攻击后没有检测到肺部病理。 ?mtrB 抵抗缺氧和酸应激的能力较差，形成生物膜的能力较差，并且在缺氧下生存力下降。通过基因微阵列分析对 ?mtrB 进行转录分析，并通过定量 RT-PCR 进行验证，表明缺氧相关的 dosR 调节子以及与结核分枝杆菌适应宿主环境相关的其他途径相关的基因下调。使用体外生化测定，我们证明 MtrB 以不依赖磷酸化的方式与 DosR（非同源 RR）相互作用。电泳迁移率变动分析表明，MtrB 增强了 DosR 与 hspX 启动子的结合，表明 MtrB 在结核分枝杆菌中 DosR 调节的基因表达中发挥着意想不到的作用。总而言之，这些发现表明 MtrB 作为 DosR 依赖性基因表达的调节剂以及结核分枝杆菌对缺氧和宿主环境的适应发挥作用。我们建议 MtrB 可以作为结核病的化疗靶点。
Paired two-component systems (TCSs), having a sensor kinase (SK) and a cognate response regulator (RR), enable the human pathogen Mycobacterium tuberculosis to respond to the external environment and to persist within its host. Here, we inactivated the SK gene of the TCS MtrAB, mtrB, generating the strain ?mtrB. We show that mtrB loss reduces the bacterium's ability to survive in macrophages and increases its association with autophagosomes and autolysosomes. Notably, the ?mtrB strain was markedly defective in establishing lung infection in mice, with no detectable lung pathology following aerosol challenge. ?mtrB was less able to withstand hypoxic and acid stresses and to form biofilms and had decreased viability under hypoxia. Transcriptional profiling of ?mtrB by gene microarray analysis, validated by quantitative RT-PCR, indicated down-regulation of the hypoxia-associated dosR regulon, as well as genes associated with other pathways linked to adaptation of M. tuberculosis to the host environment. Using in vitro biochemical assays, we demonstrate that MtrB interacts with DosR (a noncognate RR) in a phosphorylation-independent manner. Electrophoretic mobility shift assays revealed that MtrB enhances the binding of DosR to the hspX promoter, suggesting an unexpected role of MtrB in DosR-regulated gene expression in M. tuberculosis. Taken together, these findings indicate that MtrB functions as a regulator of DosR-dependent gene expression and in the adaptation of M. tuberculosis to hypoxia and the host environment. We propose that MtrB may be exploited as a chemotherapeutic target against tuberculosis.