Laboratório de Bioinorgânica, Departamento de Química Orgânica e Inorgânica, Universidade Federal do Ceará, Fortaleza, Ceará, Brazil.
UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal.
FEBS J. 2019 Nov;286(21):4278-4293. doi: 10.1111/febs.14974. Epub 2019 Jul 11.
Tuberculosis is one of the oldest known infectious diseases, responsible for millions of deaths annually around the world. The ability of Mycobacterium tuberculosis (Mtb) to enter into a dormant state has been considered integral to the success of this bacterium as a human pathogen. One of the key systems involved in regulating the entrance into dormancy is the differentially expressed in virulent strain sensor protein (DevS) [(dormancy survival sensor protein (DosS)]. However, the physiological signal for DevS has remained unclear since it was first shown to be a heme-based sensor with conflicting reports on whether it is a redox or an oxygen sensor. To address this question and provide a better understanding of the electronic properties of this protein, we present here, for the first time, a series of spectroelectrochemistry measurements of the full-length holo DevS in anaerobic conditions as well as bound to CO, NO, imidazole (Imz), cyanide, and O . An interesting feature of this protein is its ability to bind Imz even in the ferrous state, implying small-molecule analogues could be designed as potential regulators. Nonetheless, a midpoint potential (E ) value of +10 mV [vs normal hydrogen electrode (NHE)] for DevS as measured under anaerobic conditions is much higher than the expected cytosolic potential for Mtb or even within stimulated macrophages (~ -270 mV vs NHE), indicating this sensor works in a reduced ferrous state. These data, along with the high oxygen affinity and very slow auto-oxidation rate of DevS, provides evidence that it is not a redox sensor. Overall, this study validates the biological function of DevS as an oxygen sensor directly involved in the dormancy/latency of Mtb.
结核病是已知最古老的传染病之一，每年在全球造成数百万人死亡。结核分枝杆菌（Mtb）进入休眠状态的能力被认为是该细菌作为人类病原体成功的关键因素之一。参与调节进入休眠状态的关键系统之一是差异表达在毒力株传感器蛋白（DevS）[（休眠生存传感器蛋白（DosS）]。然而，自从首次表明它是一种基于血红素的传感器以来，DevS 的生理信号仍然不清楚，并且关于它是氧化还原还是氧气传感器的报告相互矛盾。为了解决这个问题，并更好地了解这种蛋白质的电子特性，我们在这里首次提出了一系列在厌氧条件下全长全同型 DevS 的光谱电化学测量，以及与 CO、NO、咪唑（Imz）、氰化物和 O 结合的光谱电化学测量。该蛋白质的一个有趣特征是它即使在亚铁状态下也能够结合 Imz，这意味着可以设计小分子类似物作为潜在的调节剂。尽管如此，在厌氧条件下测量的 DevS 的中点电位（E ）值为+10 mV [相对于标准氢电极（NHE）] 远高于 Mtb 的预期细胞内电位，甚至高于刺激的巨噬细胞内的电位（~-270 mV 相对于 NHE），表明该传感器在还原的亚铁状态下工作。这些数据，以及 DevS 的高氧亲和力和非常缓慢的自动氧化速率，表明它不是氧化还原传感器。总的来说，这项研究验证了 DevS 作为直接参与 Mtb 休眠/潜伏的氧气传感器的生物学功能。
