CooA, a CO-sensing transcription factor from Rhodospirillum rubrum, is a CO-binding heme protein
CooA, a CO-sensing transcription factor from Rhodospirillum rubrum, is a CO-binding heme protein
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DOI：
10.1073/pnas.94.21.11216
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发表时间：
1997-10-14
影响因子：
11.1
通讯作者：
Roberts, GP
中科院分区：
文献类型：
--
作者：
Shelver, D;Kerby, RL;Roberts, GP
对NO、O-2和CO等小分子的生物感知是一个重要的研究领域；然而，人们对CO的生物感知知之甚少，光合作用细菌红色红螺菌通过激活编码CO氧化系统的两个操纵子的转录来响应CO。CooA是一种转录调节蛋白，类似于cAMP受体蛋白和富马酸硝酸盐还原。在本研究中，我们报道了从其天然生物体R，Rubrum中提纯野生型CooA到95%以上的纯度。纯化的CooA在有CO存在的情况下具有序列特异性DNA结合活性，但在没有CO的情况下不具有活性。凝胶过滤实验表明，在没有CO的情况下，CooA是一个二聚体，纯化的CooA每摩尔二聚体含有1.6摩尔的血红素，当与CO相互作用时，CooA的电子光谱被干扰，表明CO与CooA的血红素直接结合。对该蛋白对CO的响应机制提出了一个假说。
Biological sensing of small molecules such as NO, O-2, and CO is an important area of research; however, little is know about how CO is sensed biologically, The photosynthetic bacterium Rhodospirillum rubrum responds to CO by activating transcription of two operons that encode a CO-oxidizing system. A protein, CooA has been identified as necessary for this response, CooA is a member of a family of transcriptional regulators similar to the cAMP receptor protein and fumavate nitrate reduction from Escherichia coli, In this study we report the purification of wild-type CooA from its native organism, R, rubrum, to greater than 95% purity, The purified protein is active in sequence-specific DNA binding in the presence of CO, but not in the absence of CO, Gel filtration experiments reveal the protein to be a dimer in the absence of CO, Purified CooA contains 1.6 mol heme per mol of dimer, Upon interacting with CO, the electronic spectrum of CooA is perturbed, indicating the direct binding of CO to the heme of CooA. A hypothesis for the mechanism of the protein's response to CO is proposed.