The nitrate reductase and nitrite reductase operons and the narT gene of Staphylococcus carnosus are positively controlled by the novel two-component system NreBC
The nitrate reductase and nitrite reductase operons and the narT gene of Staphylococcus carnosus are positively controlled by the novel two-component system NreBC
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DOI：
10.1128/jb.184.23.6624-6634.2002
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发表时间：
2002-12-01
影响因子：
3.2
通讯作者：
Götz, F
中科院分区：
文献类型：
--
作者：
Fedtke, I;Kamps, A;Götz, F
在肉葡萄球菌中，nreABC（用于氮调节）基因被鉴定并显示连接硝酸还原酶操纵子（narGHJI）和推定的硝酸盐转运蛋白基因narT。一个nreABC缺失突变体，M1，显着影响硝酸盐和亚硝酸盐还原和生长。narT，narGHJI，和亚硝酸还原酶（NIR）操纵子的转录严重减少，即使在无硝酸盐或亚硝酸盐的厌氧培养细胞。当细胞在有氧或厌氧条件下生长时，在有或没有硝酸盐或亚硝酸盐的情况下检测到nreABC转录物。NreA是一种功能未知的含有GAF结构域的蛋白质。体内和体外研究表明，NreC被NreB磷酸化，磷酸化NreC特异性结合富含GC的回文序列，以增强转录起始。这种结合基序被发现在narGHJI，nir和narT启动子，但不是在moeB启动子。NreB是具有四个N-末端半胱氨酸残基的胞质蛋白。第二个半胱氨酸残基被证明是重要的NreB功能。体外NreB的自磷酸化不受硝酸盐、亚硝酸盐或亚硝酸盐的影响。nir启动子活性是铁依赖性的。这些数据为对有氧和无氧代谢重要的全球调节系统提供了证据，其中NreB和NreC形成了经典的双组分系统，NreB充当传感蛋白，氧作为效应分子。
In Staphylococcus carnosus, the nreABC (for nitrogen regulation) genes were identified and shown to link the nitrate reductase operon (narGHJI and the putative nitrate transporter gene narT. An nreABC deletion mutant, m1, was dramatically affected in nitrate and nitrite reduction and growth. Transcription of narT, narGHJI, and the nitrite reductase (nir) operon was severely reduced even when cells were cultivated anaerobically without nitrate or nitrite. nreABC transcripts were detected when cells were grown aerobically or anaerobically with or without nitrate or nitrite. NreA is a GAF domain-containing protein of unknown function. In vivo and in vitro studies showed that NreC is phosphorylated by NreB and that phospho-NreC specifically binds to a GC-rich palindromic sequence to enhance transcription initiation. This binding motif was found at the narGHJI, nir, and narT promoters but not at the moeB promoter. NreB is a cytosolic protein with four N-terminal cysteine residues. The second cysteine residue was shown to be important for NreB function. In vitro autophosphorylation of NreB was not affected by nitrate, nitrite, or molybdate. The nir promoter activity was iron dependent. The data provide evidence for a global regulatory system important for aerobic and anaerobic metabolism, with NreB and NreC forming a classical two-component system and NreB acting as a sensor protein with oxygen as the effector molecule.