Three Pseudomonas putida FNR Family Proteins with Different Sensitivities to O2.
Three Pseudomonas putida FNR Family Proteins with Different Sensitivities to O2.
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DOI：
10.1074/jbc.m115.654079
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发表时间：
2015-07-03
期刊：
影响因子：
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通讯作者：
Green J
中科院分区：
文献类型：
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作者：
Ibrahim SA;Crack JC;Rolfe MD;Borrero-de Acuña JM;Thomson AJ;Le Brun NE;Schobert M;Stapleton MR;Green J
背景：FNR蛋白是O2响应性细菌转录因子。结果：恶臭假单胞菌具有3种对O2敏感性不同的铁硫簇FNR蛋白。结论：FNR蛋白与O2的铁硫簇反应机制是保守的。意义：多种FNR蛋白的差异敏感性扩展了单个细菌内O2响应基因表达的范围。大肠杆菌硝酸盐还原调节因子（FNR）蛋白是细菌O2敏感转录因子的范例。然而，与E.在大肠杆菌中，一些细菌物种具有多个FNR蛋白，这些蛋白可能已经进化以实现不同的作用。在这里，三个FNR蛋白质（ANR，PP_3233，和PP_3287）从一个单一的细菌物种，恶臭假单胞菌KT 2440，进行了分析。在厌氧条件下，所有三种蛋白质的光谱特性类似于[4Fe-4S]蛋白质。ANR [4Fe-4S]簇合物与O2的反应性与E. coli FNR，并在转化为脱辅基蛋白的过程中，通过[2Fe-2S]中间体，保留了簇硫。与ANR类似，当暴露于O2时，重构的PP_3233和PP_3287转化为[2Fe-2S]形式，但它们的[4Fe-4S]簇反应较慢。从恶臭假单胞菌和大肠杆菌中具有共有FNR结合位点的FNR依赖性启动子转录。仅表达一种FNR蛋白的大肠杆菌菌株与体外对O2的反应一致。综上所述，实验结果表明，不同恶臭假单胞菌FNR蛋白中铁硫簇的局部环境影响它们与O2的反应性，使得ANR类似于E. coli FNR，对低浓度O2高度敏感，而PP_3233和PP_3287对O2的敏感性较低。
Background: FNR proteins are O2-responsive bacterial transcription factors. Results: Pseudomonas putida possesses three FNR proteins with iron-sulfur clusters that have different sensitivities to O2. Conclusion: The mechanism of the iron-sulfur cluster reaction with O2 is conserved among FNR proteins. Significance: Differential sensitivity of multiple FNR proteins extends the range of O2-responsive gene expression within a single bacterium. The Escherichia coli fumarate-nitrate reduction regulator (FNR) protein is the paradigm for bacterial O2-sensing transcription factors. However, unlike E. coli, some bacterial species possess multiple FNR proteins that presumably have evolved to fulfill distinct roles. Here, three FNR proteins (ANR, PP_3233, and PP_3287) from a single bacterial species, Pseudomonas putida KT2440, have been analyzed. Under anaerobic conditions, all three proteins had spectral properties resembling those of [4Fe-4S] proteins. The reactivity of the ANR [4Fe-4S] cluster with O2 was similar to that of E. coli FNR, and during conversion to the apo-protein, via a [2Fe-2S] intermediate, cluster sulfur was retained. Like ANR, reconstituted PP_3233 and PP_3287 were converted to [2Fe-2S] forms when exposed to O2, but their [4Fe-4S] clusters reacted more slowly. Transcription from an FNR-dependent promoter with a consensus FNR-binding site in P. putida and E. coli strains expressing only one FNR protein was consistent with the in vitro responses to O2. Taken together, the experimental results suggest that the local environments of the iron-sulfur clusters in the different P. putida FNR proteins influence their reactivity with O2, such that ANR resembles E. coli FNR and is highly responsive to low concentrations of O2, whereas PP_3233 and PP_3287 have evolved to be less sensitive to O2.