Nitric oxide in chemostat-cultured Escherichia coli is sensed by Fnr and other global regulators:: Unaltered methionine biosynthesis indicates lack of S nitrosation
Nitric oxide in chemostat-cultured Escherichia coli is sensed by Fnr and other global regulators:: Unaltered methionine biosynthesis indicates lack of S nitrosation
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DOI：
10.1128/jb.01354-06
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发表时间：
2007-03-01
影响因子：
3.2
通讯作者：
Poole, Robert K.
中科院分区：
文献类型：
--
作者：
Pullan, Steven T.;Gidley, Mark D.;Poole, Robert K.
我们之前阐明了大肠杆菌在需氧和厌氧恒化器中对亚硝化剂 S-亚硝基谷胱甘肽 (GSNO) 的整体转录反应，证明了一氧化氮 (NO) 保护机制的表达，并获得了关键硫醇亚硝化的证据。本研究首次在恒化器中检查暴露于 NO 的大肠杆菌的转录组。使用相同的条件，我们将GSNO刺激物与两种NO供体化合物{3[2-羟基-1-(1-甲基-乙基)-2-亚硝基肼基]-1-丙胺(NOC-5)和3-(2-羟基-1-甲基-2-亚硝基肼基)-N-甲基-1-丙胺(NOC-7)}同时释放的NO刺激物进行了比较，并证明了转录反应存在显着差异。这些独特的亚硝化应激。暴露于 NO 不会诱导 met 基因，这表明与 GSNO 不同，NO 不会引起同型半胱氨酸 S 亚硝化和蛋氨酸生物合成的代偿性增加。进入细胞后，外源蛋氨酸提供保护，防止 GSNO 介导的杀伤，但不能防止 NO 介导的杀伤。厌氧暴露于 NO 会导致多个 Fnr 抑制基因的上调和 Fnr 激活基因的下调，其中包括编码细胞色素 C 亚硝酸还原酶的 nrfA，这提供了 NO 不存在 Fur 失活的有力证据。其他明显受 NO 影响的全球监管机构包括 IscR、Fur、SoxR、NsrR 和 NorR。我们尝试通过对暴露于 NO 的野生型菌株和 NorR 突变菌株进行微阵列比较来鉴定 NorR 调节子的组成部分；只有norVW，编码NO解毒的flareubredoxin及其同源还原酶，被明确识别。 norV 或norR 突变对小鼠巨噬细胞中大肠杆菌的存活没有影响。因此，GSNO（亚硝化剂）和 NO 具有不同的细胞作用； NO 更有效地与调节亚硝化应激适应性反应的全局调节因子相互作用，但不影响同型半胱氨酸亚硝化产生的蛋氨酸需求。
We previously elucidated the global transcriptional responses of Escherichia coli to the nitrosating agent S-nitrosoglutathione (GSNO) in both aerobic and anaerobic chemostats, demonstrated the expression of nitric oxide (NO)-protective mechanisms, and obtained evidence of critical thiol nitrosation. The present study was the first to examine the transcriptome of NO-exposed E. coli in a chemostat. Using identical conditions, we compared the GSNO stimulon with the stimulon of NO released from two NO donor compounds {3[2-hydroxy-1-(1-methyl-ethyl)-2-nitrosohydrazino]-1-propanamine (NOC-5) and 3-(2-hydroxy-l-methyl-2-nitrosohydrazino)-N-methyl-1-propanamine (NOC-7)} simultaneously and demonstrated that there were marked differences in the transcriptional responses to these distinct nitrosative stresses. Exposure to NO did not induce met genes, suggesting that, unlike GSNO, NO does not elicit homocysteine S nitrosation and compensatory increases in methionine biosynthesis. After entry into cells, exogenous methionine provided protection from GSNO-mediated killing but not from NO-mediated killing. Anaerobic exposure to NO led to up-regulation of multiple Fnr-repressed genes and down-regulation of Fnr-activated genes, including nrfA, which encodes cytochrome c nitrite reductase, providing strong evidence that there is NO inactivation of Fur. Other global regulators apparently affected by NO were IscR, Fur, SoxR, NsrR, and NorR. We tried to identify components of the NorR regulon by performing a microarray comparison of NO-exposed wild-type and norR mutant strains; only norVW, encoding the NO-detoxifying flavorubredoxin and its cognate reductase, were unambiguously identified. Mutation of norV or norR had no effect on E. coli survival in mouse macrophages. Thus, GSNO (a nitrosating agent) and NO have distinct cellular effects; NO more effectively interacts with global regulators that mediate adaptive responses to nitrosative stress but does not affect methionine requirements arising from homocysteine nitrosation.