2月13日的《公共科學圖書館·綜合》（PLoS ONE）雜志刊登了中國科學院北京基因組研究所基因組科學及信息重點實驗室胡松年研究員與浙江大學華躍進研究員共同指導完成的文章——A Novel OxyR Sensor and Regulator of Hydrogen Peroxide Stress with One Cysteine Residue in Deinococcus radiodurans,。
耐輻射球菌(Deinococcus radiodurans)是迄今為止發(fā)現(xiàn)的對電離輻射,、紫外線、過氧化氫等一些DNA損傷劑都具有極強抗性的微小球菌。公認的耐輻射球菌有3種DNA修復方式：堿基切除修復,、核苷酸切除修復和重組修復。但DNA修復過程的啟動機制和修復的分子機理卻知之甚少,。
在細菌中,，OxyR是過氧化物受體和轉錄調(diào)節(jié)元件，它能感受活性氧的存在并誘導抗氧化系統(tǒng)的功能,。當細胞感受到時,，OxyR蛋白通過兩個保守的半胱氨酸殘基（C199和C208）的二硫鍵的形成而被激活，在耐輻射球菌中,，發(fā)現(xiàn)了一個基因DrOxyR基因具有特殊的特征,，即它只有一個保守的半胱氨酸。Dr0615的突變體對H2O2表現(xiàn)超敏感,，但對電離輻射不甚敏感,。定點突變和體內(nèi)功能分析表明，DrOxyR蛋白的C210對感受H2O2是必須的,，定量PCR和轉錄豐度分析表明,，DrOxyR既是轉錄激活子也是轉錄抑制子，能調(diào)節(jié)Mn/Fe的平衡,。本研究表明,，OxyR家族基因可以分為兩類：2-Cys類和1-Cys類. （來源：中科院北京基因組所）
（《公共科學圖書館·綜合》（PLoS ONE），doi:10.1371/journal.pone.0001602,，Huan Chen, Songnian Hu, Yuejin Hua）
生物谷推薦原始出處：
A Novel OxyR Sensor and Regulator of Hydrogen Peroxide Stress with One Cysteine Residue in Deinococcus radiodurans
Huan Chen1,2, Guangzhi Xu1, Ye Zhao1, Bing Tian1, Huiming Lu1, Xiaomin Yu3, Zhenjian Xu1, Nanjiao Ying1, Songnian Hu2,3*, Yuejin Hua1*
1 Key Laboratory of Chinese Ministry of Agriculture for Nuclear-Agricultural Sciences, Institute of Nuclear-Agricultural Sciences, Zhejiang University, China, 2 James D. Watson Institute of Genome Sciences, Zhejiang University, Hangzhou, China, 3 Key Laboratory of Genome Science and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China
Abstract
In bacteria, OxyR is a peroxide sensor and transcription regulator, which can sense the presence of reactive oxygen species and induce antioxidant system. When the cells are exposed to H2O2, OxyR protein is activated via the formation of a disulfide bond between the two conserved cysteine residues (C199 and C208). In Deinococcus radiodurans, a previously unreported special characteristic of DrOxyR (DR0615) is found with only one conserved cysteine. dr0615 gene mutant is hypersensitive to H2O2, but only a little to ionizing radiation. Site-directed mutagenesis and subsequent in vivo functional analyses revealed that the conserved cysteine (C210) is necessary for sensing H2O2, but its mutation did not alter the binding characteristics of OxyR on DNA. Under oxidant stress, DrOxyR is oxidized to sulfenic acid form, which can be reduced by reducing reagents. In addition, quantitative real-time PCR and global transcription profile results showed that OxyR is not only a transcriptional activator (e.g., katE, drb0125), but also a transcriptional repressor (e.g., dps, mntH). Because OxyR regulates Mn and Fe ion transporter genes, Mn/Fe ion ratio is changed in dr0615 mutant, suggesting that the genes involved in Mn/Fe ion homeostasis, and the genes involved in antioxidant mechanism are highly cooperative under extremely oxidant stress. In conclusion, these findings expand the OxyR family, which could be divided into two classes: typical 2-Cys OxyR and 1-Cys OxyR.
全文鏈接：
http://www.plosone.org/article/fetchArticle.action?articleURI=info:doi/10.1371/journal.pone.0001602
