Proteins needed to activate a transcriptional response to the reactive oxygen species singlet oxygen.
Proteins needed to activate a transcriptional response to the reactive oxygen species singlet oxygen.
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DOI：
10.1128/mbio.00541-12
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发表时间：
2013-01-08
期刊：
影响因子：
6.4
通讯作者：
Donohue TJ
中科院分区：
文献类型：
--
作者：
Nam TW;Ziegelhoffer EC;Lemke RA;Donohue TJ
单线态氧 (1O2) 是一种活性氧，由一个或多个激发供体的能量转移到分子氧而产生。许多生物分子容易被 1O2 氧化，细胞已经进化出系统来保护自己免受这种化合物造成的损害。光合细菌球形红杆菌保护自身免受 1O2 侵害的一种方法是诱导由 ChrR 控制的转录反应，ChrR 是一种抗 σ 因子，在 1O2 存在的情况下会释放另一种 σ 因子 σE。在此，我们报道，当 σE 调节子中的两个保守基因被删除时，在 1O2 存在的情况下，σE 依赖性基因转录的诱导会减少，其中包括一个编码环丙烷脂肪酸合酶同源物 (RSP2144) 或一个编码未知功能的蛋白质 (RSP1091)。因此，我们得出结论，在 1O2 存在的情况下，RSP2144 和 RSP1091 都是增加 σE 活性所必需的。此外，我们发现，与野生型细胞不同，在野生型细胞中，当 1O2 产生时 ChrR 会迅速降解，而当缺乏 RSP2144、RSP1091 或这两种蛋白的细胞暴露于 1O2 时，这种抗 σ 因子的周转速度会减慢。此外，我们证明有机氢过氧化物叔丁基氢过氧化物促进野生型细胞和缺乏RSP2144或RSP1091的突变体中的ChrR转换，这表明不同类型的氧化剂增加σE活性的方式存在差异。氧气在地球上发挥着许多重要的作用。它是在光合作用过程中产生的，并且是其他途径所需要的。虽然氧气相对惰性，但它可以转化为活性氧 (ROS)，从而破坏生物分子、引起疾病或杀死细胞。当能量转移到氧气时，会产生 ROS 单线态氧。为了了解单线态氧如何影响细胞，我们研究了球形红杆菌对这种 ROS 的应激反应，这种细菌像植物一样，通过光合作用产生这种化合物。本文鉴定了激活对单线态氧应激反应的蛋白质，并表明它们对这种 ROS 做出特定反应。已鉴定的蛋白质存在于许多在自然界中可以遇到单线态氧的自由生活、共生或病原细菌中。因此，我们的研究结果提供了有关对 ROS 的应激反应的新信息，具有广泛的生物学、农业和生物医学重要性。
Singlet oxygen (1O2) is a reactive oxygen species generated by energy transfer from one or more excited donors to molecular oxygen. Many biomolecules are prone to oxidation by 1O2, and cells have evolved systems to protect themselves from damage caused by this compound. One way that the photosynthetic bacterium Rhodobacter sphaeroides protects itself from 1O2 is by inducing a transcriptional response controlled by ChrR, an anti-σ factor which releases an alternative sigma factor, σE, in the presence of 1O2. Here we report that induction of σE-dependent gene transcription is decreased in the presence of 1O2 when two conserved genes in the σE regulon are deleted, including one encoding a cyclopropane fatty acid synthase homologue (RSP2144) or one encoding a protein of unknown function (RSP1091). Thus, we conclude that RSP2144 and RSP1091 are each necessary to increase σE activity in the presence of 1O2. In addition, we found that unlike in wild-type cells, where ChrR is rapidly degraded when 1O2 is generated, turnover of this anti-σ factor is slowed when cells lacking RSP2144, RSP1091, or both of these proteins are exposed to 1O2. Further, we demonstrate that the organic hydroperoxide tert-butyl hydroperoxide promotes ChrR turnover in both wild-type cells and mutants lacking RSP2144 or RSP1091, suggesting differences in the ways different types of oxidants increase σE activity. Oxygen serves many crucial functions on Earth; it is produced during photosynthesis and needed for other pathways. While oxygen is relatively inert, it can be converted to reactive oxygen species (ROS) that destroy biomolecules, cause disease, or kill cells. When energy is transferred to oxygen, the ROS singlet oxygen is generated. To understand how singlet oxygen impacts cells, we study the stress response to this ROS in Rhodobacter sphaeroides, a bacterium that, like plants, generates this compound as a consequence of photosynthesis. This paper identifies proteins that activate a stress response to singlet oxygen and shows that they act in a specific response to this ROS. The identified proteins are found in many free-living, symbiotic, or pathogenic bacteria that can encounter singlet oxygen in nature. Thus, our findings provide new information about a stress response to a ROS of broad biological, agricultural, and biomedical importance.