Expression of nitrous oxide reductase in Paracoccus denitrificans is regulated by oxygen and nitric oxide through FnrP and NNR.
Expression of nitrous oxide reductase in Paracoccus denitrificans is regulated by oxygen and nitric oxide through FnrP and NNR.
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DOI：
10.1099/mic.0.054148-0
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发表时间：
2012-03
期刊：
影响因子：
--
通讯作者：
Bakken LR
中科院分区：
文献类型：
--
作者：
Bergaust L;van Spanning RJM;Frostegård Å;Bakken LR
进行反硝化的四个步骤的还原酶由转录调节因子和辅助因子的网络控制，所述转录调节因子和辅助因子响应于细胞内和细胞外信号，其中包括氧和N氧化物（NO和）。虽然已经确定了调控网络的许多组成部分，但我们对它们在控制各种还原酶，特别是环境重要的N2 O还原酶（N2 OR）表达中的作用的理解存在差距。我们研究了在以下方面缺陷的副球菌的反硝化表型：（i）调节蛋白（三种FNR型转录调节因子，NarR，NNR和FnrP，以及NirI，其参与结构nir簇的转录激活）;（ii）功能酶（NO还原酶和N2 OR）;或（iii）参与N2 O还原的辅助因子（NirX和NosX）。一个自动化的孵化系统使我们能够密切监测从好氧呼吸到缺氧呼吸过渡期间氧气和所有气体产物浓度的变化。在NO还原酶缺陷的菌株能够生长在反硝化过程中，尽管达到微摩尔浓度的NO，但无法返回到好氧呼吸。FnrP突变体在以硝酸盐为唯一氮氧化物的培养基中呈线性缺氧生长，但通过用亚硝酸盐代替硝酸盐来恢复指数生长。我们将其解释为亚硝酸盐限制，这表明呼吸硝酸还原酶（NAR）的FnrP和NarR的双重转录控制。NirX或NosX中的突变不影响表型，但双突变体缺乏减少N2 O的潜力。最后，我们发现FnrP和NNR是N2 OR的替代和同等有效的诱导剂。
The reductases performing the four steps of denitrification are controlled by a network of transcriptional regulators and ancillary factors responding to intra- and extracellular signals, amongst which are oxygen and N oxides (NO and ). Although many components of the regulatory network have been identified, there are gaps in our understanding of their role(s) in controlling the expression of the various reductases, in particular the environmentally important N2O reductase (N2OR). We investigated denitrification phenotypes of Paracoccus denitrificans mutants deficient in: (i) regulatory proteins (three FNR-type transcriptional regulators, NarR, NNR and FnrP, and NirI, which is involved in transcription activation of the structural nir cluster); (ii) functional enzymes (NO reductase and N2OR); or (iii) ancillary factors involved in N2O reduction (NirX and NosX). A robotized incubation system allowed us to closely monitor changes in concentrations of oxygen and all gaseous products during the transition from oxic to anoxic respiration. Strains deficient in NO reductase were able to grow during denitrification, despite reaching micromolar concentrations of NO, but were unable to return to oxic respiration. The FnrP mutant showed linear anoxic growth in a medium with nitrate as the sole NOx, but exponential growth was restored by replacing nitrate with nitrite. We interpret this as nitrite limitation, suggesting dual transcriptional control of respiratory nitrate reductase (NAR) by FnrP and NarR. Mutations in either NirX or NosX did not affect the phenotype, but the double mutant lacked the potential to reduce N2O. Finally, we found that FnrP and NNR are alternative and equally effective inducers of N2OR.
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影响因子：
4.8
作者：
Corker, H;Poole, RK
通讯作者：
Poole, RK
影响因子：
3.6
作者：
VanSpanning, RJM;DeBoer, APN;VanDerOost, J
通讯作者：
VanDerOost, J
影响因子：
5.1
作者：
Bergaust, Linda;Shapleigh, James;Bakken, Lars
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Bakken, Lars
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4.1
作者：
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3.2
作者：
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