Biochemical properties of Paracoccus denitrificans FnrP: reactions with molecular oxygen and nitric oxide.
Biochemical properties of Paracoccus denitrificans FnrP: reactions with molecular oxygen and nitric oxide.
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DOI：
10.1007/s00775-015-1326-7
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发表时间：
2016-03
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影响因子：
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通讯作者：
Le Brun NE
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作者：
Crack JC;Hutchings MI;Thomson AJ;Le Brun NE
在副球菌中，三种CRP/FNR家族调节蛋白NarR、NnrR和FnrP控制好氧和厌氧（反硝化）呼吸之间的转换。FnrP是来自E.大肠杆菌，并相应地调节编码有氧和无氧呼吸酶的基因，以响应O2和NO的可用性。在这里，我们表明，FnrP经历O2驱动的[4Fe-4S]到[2Fe-2S]簇转换，涉及到每个簇2 O2，在较高的O2浓度下观察到的释放簇硫化物到硫烷的显着氧化。簇合反应的速率比大肠杆菌低约6倍。coli FNR中表达，表明FnrP在微需氧条件下仍能保持转录活性。这与FnrP在微需氧条件下激活高O2亲和力细胞色素c氧化酶表达的作用一致。簇转化导致转录活性FnrP二聚体解离成单体。因此，沿着E. coli FNR中FnrP属于FNR蛋白的一个亚类，其簇型与结合状态有关。有趣的是，两个关键的带电残基，Arg 140和Asp 154，已被证明在E. coli FNR在FnrP中不保守，表明不同的原聚体相互作用对这种平衡很重要。最后，FnrP [4Fe-4S]簇被示出与多个NO分子进行反应，导致铁亚硝酰基物种和解离成单体。本文的在线版本（doi：10.1007/s 00775 -015-1326-7）包含补充材料，可供授权用户使用。
In Paracoccus denitrificans, three CRP/FNR family regulatory proteins, NarR, NnrR and FnrP, control the switch between aerobic and anaerobic (denitrification) respiration. FnrP is a [4Fe–4S] cluster-containing homologue of the archetypal O2 sensor FNR from E. coli and accordingly regulates genes encoding aerobic and anaerobic respiratory enzymes in response to O2, and also NO, availability. Here we show that FnrP undergoes O2-driven [4Fe–4S] to [2Fe–2S] cluster conversion that involves up to 2 O2 per cluster, with significant oxidation of released cluster sulfide to sulfane observed at higher O2 concentrations. The rate of the cluster reaction was found to be ~sixfold lower than that of E. coli FNR, suggesting that FnrP can remain transcriptionally active under microaerobic conditions. This is consistent with a role for FnrP in activating expression of the high O2 affinity cytochrome c oxidase under microaerobic conditions. Cluster conversion resulted in dissociation of the transcriptionally active FnrP dimer into monomers. Therefore, along with E. coli FNR, FnrP belongs to the subset of FNR proteins in which cluster type is correlated with association state. Interestingly, two key charged residues, Arg140 and Asp154, that have been shown to play key roles in the monomer–dimer equilibrium in E. coli FNR are not conserved in FnrP, indicating that different protomer interactions are important for this equilibrium. Finally, the FnrP [4Fe–4S] cluster is shown to undergo reaction with multiple NO molecules, resulting in iron nitrosyl species and dissociation into monomers. The online version of this article (doi:10.1007/s00775-015-1326-7) contains supplementary material, which is available to authorized users.