Mycobacterium tuberculosis Pst/SenX3-RegX3 Regulates Membrane Vesicle Production Independently of ESX-5 Activity.
Mycobacterium tuberculosis Pst/SenX3-RegX3 Regulates Membrane Vesicle Production Independently of ESX-5 Activity.
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DOI：
10.1128/mbio.00778-18
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发表时间：
2018-06-12
期刊：
影响因子：
6.4
通讯作者：
Tischler AD
中科院分区：
文献类型：
--
作者：
White DW;Elliott SR;Odean E;Bemis LT;Tischler AD
结核分枝杆菌释放膜囊泡（MV），调节宿主的免疫反应，并在铁的收购援助，虽然他们可能有额外的不受重视的功能。MV生产似乎是一个受调节的过程，但virR仍然是唯一的特征遗传调节囊泡形成。在这里，我们提出的数据支持的M的作用。结核菌Pst/SenX 3-RegX 3信号转导系统调控MV的产生。缺失pstA 1（其编码磷酸盐特异性转运（Pst）系统的跨膜组分）导致SenX 3-RegX 3双组分系统的组成性激活，从而导致通过专门的ESX-5 VII型分泌系统增加蛋白质分泌。使用蛋白质组学质谱，我们鉴定了Δ pstA 1突变体超分泌的几种其他蛋白质，包括MV相关脂蛋白LpqH。纳米颗粒跟踪分析显示，Δ pstA 1突变体的MV产量增加了15倍。LpqH的过度分泌和MV释放的增加都需要RegX 3，但不依赖于VirR，这表明Pst/SenX 3-RegX 3通过一种新的机制控制MV释放。先前的蛋白质组学分析鉴定了与MV相关的ESX-5底物。因此，我们假设MV释放需要ESX-5活动。我们构建了有条件表达eccD 5的菌株，eccD 5编码预测的ESX-5跨膜通道。在EccD 5耗尽后，我们观察到ESX-5底物EsxN和PPE 41的分泌减少，但MV释放不受影响。我们的数据表明，ESX-5不影响囊泡的生产，并意味着进一步表征Pst/SenX 3-RegX 3调节子可能揭示新的机制，M。结核囊泡生物发生。在革兰氏阴性菌中，来自外膜的MV在细菌生理学和致病性中具有多种功能，并且已经鉴定了调节其产生的几种因子。虽然革兰氏阳性菌和分枝杆菌，缺乏外膜也产生囊泡的发病机制中描述的作用，MV在这些生物体的生物合成的机制仍然很差的特点。定义MV生物发生的机制可能会产生显着的见解MV生产过程中感染的重要性。In M.在结核病中，已知只有单个遗传元件virR调节MV产生。我们的工作表明，Pst/SenX 3-RegX 3信号转导系统是一种新的MV生物合成的调节剂，它通过一种独立于VirR和特异性ESX-5蛋白分泌系统激活的机制控制MV的产生。了解RegX 3调节子中哪些基因导致MV产生增加可能揭示MV释放的新分子机制。
Mycobacterium tuberculosis releases membrane vesicles (MV) that modulate host immune responses and aid in iron acquisition, although they may have additional unappreciated functions. MV production appears to be a regulated process, but virR remains the only characterized genetic regulator of vesiculogenesis. Here, we present data supporting a role for the M. tuberculosis Pst/SenX3-RegX3 signal transduction system in regulating MV production. Deletion of pstA1, which encodes a transmembrane component of the phosphate-specific transport (Pst) system, causes constitutive activation of the SenX3-RegX3 two-component system, leading to increased protein secretion via the specialized ESX-5 type VII secretion system. Using proteomic mass spectrometry, we identified several additional proteins hyper-secreted by the ΔpstA1 mutant, including LpqH, an MV-associated lipoprotein. Nanoparticle tracking analysis revealed a 15-fold increase in MV production by the ΔpstA1 mutant. Both hyper-secretion of LpqH and increased MV release required RegX3 but were independent of VirR, suggesting that Pst/SenX3-RegX3 controls MV release by a novel mechanism. Prior proteomic analysis identified ESX-5 substrates associated with MV. We therefore hypothesized that MV release requires ESX-5 activity. We constructed strains that conditionally express eccD5, which encodes the predicted ESX-5 transmembrane channel. Upon EccD5 depletion, we observed reduced secretion of the ESX-5 substrates EsxN and PPE41, but MV release was unaffected. Our data suggest that ESX-5 does not affect vesicle production and imply that further characterization of the Pst/SenX3-RegX3 regulon might reveal novel mechanisms of M. tuberculosis vesicle biogenesis. In Gram-negative bacteria, MV derived from the outer membrane have diverse functions in bacterial physiology and pathogenesis, and several factors regulating their production have been identified. Though Gram-positive bacteria and mycobacteria that lack an outer membrane also produce vesicles with described roles in pathogenesis, the mechanisms of MV biogenesis in these organisms remain poorly characterized. Defining mechanisms of MV biogenesis might yield significant insights into the importance of MV production during infection. In M. tuberculosis, only a single genetic element, virR, is known to regulate MV production. Our work reveals that the Pst/SenX3-RegX3 signal transduction system is a novel regulator of MV biogenesis that controls MV production by a mechanism that is independent of both VirR and activation of the specialized ESX-5 protein secretion system. Understanding which genes in the RegX3 regulon cause increased MV production might reveal novel molecular mechanisms of MV release.