DosT and DevS are oxygen-switched kinases in Mycobacterium tuberculosis
DosT and DevS are oxygen-switched kinases in Mycobacterium tuberculosis
复制标题
DOI：
10.1110/ps.072897707
复制
发表时间：
2007-08-01
期刊：
影响因子：
8
通讯作者：
Gilles-Gonzalez, Marie-Alda
中科院分区：
文献类型：
--
作者：
Sousa, Eduardo Henrique Silva;Tuckerman, Jason Robert;Gilles-Gonzalez, Marie-Alda
已知结核分枝杆菌暴露于缺氧会通过转录因子DevR（也称为DosR）改变许多基因的表达，包括被认为参与潜伏期的基因。两种感觉激酶DoS和DevS（也称为DoS）控制DevR的活性。我们发现，像DevS，DoS包含一个血红素辅因子内的N-末端GAF域。对于全长DoS和DevS，我们确定了配体结合参数和ATP与配体和非配体状态的反应速率。在这两种蛋白质中，血红素状态与激酶偶联，使得未配体的、CO结合的和NO结合的形式是活性的，但O-2结合的形式是无活性的。氧结合的DosT对氧化成铁态是异常惰性的（在空气中的半衰期> 60小时）。虽然DosT的激酶活性不受NO的影响，但该配体与DosT的结合比O-2强5000倍（K-d [NO]类似于5 nM，而K-d [O-2] = 26 μ M）。这些结果证明了M中蛋白质的直接和特异性O-2传感。结核病，并确定了第一次从这种生物体的感觉激酶的信号配体。这也解释了为什么M.在有氧条件下将肺结核转化为NO供体可以得到与缺氧相同的结果，即，NO使DosT饱和，阻止O-2结合并产生活性激酶。
Exposure of Mycobacterium tuberculosis to hypoxia is known to alter the expression of many genes, including ones thought to be involved in latency, via the transcription factor DevR (also called DosR). Two sensory kinases, DosT and DevS (also called DosS), control the activity of DevR. We show that, like DevS, DosT contains a heme cofactor within an N-terminal GAF domain. For full-length DosT and DevS, we determined the ligand- binding parameters and the rates of ATP reaction with the liganded and unliganded states. In both proteins, the heme state was coupled to the kinase such that the unliganded, CO-bound, and NO-bound forms were active, but the O-2-bound form was inactive. Oxygen-bound DosT was unusually inert to oxidation to the ferric state ( half life in air > 60 h). Though the kinase activity of DosT was unaffected by NO, this ligand bound 5000 times more avidly than O-2 to DosT (K-d [NO] similar to 5 nM versus K-d [O-2] = 26 mu M). These results demonstrate direct and specific O-2 sensing by proteins in M. tuberculosis and identify for the first time a signal ligand for a sensory kinase from this organism. They also explain why exposure of M. tuberculosis to NO donors under aerobic conditions can give results identical to hypoxia, i.e., NO saturates DosT, preventing O-2 binding and yielding an active kinase.