Polynucleotide phosphorylase protects Escherichia coli against oxidative stress.
Polynucleotide phosphorylase protects Escherichia coli against oxidative stress.
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DOI：
10.1021/bi801752p
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发表时间：
2009-03-10
期刊：
影响因子：
2.9
通讯作者：
Li, Zhongwei
中科院分区：
文献类型：
--
作者：
Wu, Jinhua;Jiang, Zhe;Liu, Min;Gong, Xin;Wu, Shaohui;Burns, Christopher M.;Li, Zhongwei
大肠杆菌多核苷酸磷酸化酶（PNPase）主要在RNA降解中起作用。它是一种外核糖核酸酶，是多酶RNA降解复合物的组成部分[Carpousis et al. (1994) Cell 76, 889]。先前有研究表明PNPase可以特异性结合含有氧化损伤8-羟基鸟嘌呤（8-oxoG）的合成RNA [Hayakawa等人（2001），Biochemistry 40,9977]，这表明PNPase可能在去除氧化损伤RNA中起作用。在这里，我们发现PNPase与合成后过氧化氢（H2O2）处理氧化损伤的自然序列RNA分子结合。PNPase结合氧化RNA的亲和力高于未处理的相同序列的RNA，提高了它可能对多种病变起作用的可能性。这种保护作用的重要性可以通过观察来说明，在已知引起细胞质组分氧化损伤的条件下，pnpase缺陷细胞的存活率低于野生型细胞。此外，当受到H2O2刺激时，pnpase缺陷细胞在细胞RNA中积累8-oxoG的程度高于野生型细胞，这表明该RNase在体内发挥最小化氧化RNA的作用。引入编码PNPase的pnp基因可改善pnp突变细胞的生长缺陷和RNA质量。我们的研究结果还表明，抗氧化应激是PNPase的内在功能，因为它不需要与RNA降解体或RNA解旋酶B （RhlB）结合。
Escherichia coli polynucleotide phosphorylase (PNPase) primarily functions in RNA degradation. It is an exoribonuclease and integral component of the multienzyme RNA degradosome complex [Carpousis et al. (1994) Cell 76, 889]. PNPase was previously shown to specifically bind a synthetic RNA containing the oxidative lesion 8-hydroxyguanine (8-oxoG) [Hayakawa et al. (2001) Biochemistry 40, 9977], suggesting a possible role in removing oxidatively damaged RNA. Here we show that PNPase binds to RNA molecules of natural sequence that were oxidatively damaged by treatment with hydrogen peroxide (H2O2) postsynthetically. PNPase bound oxidized RNA with higher affinity than untreated RNA of the same sequence, raising the possibility that it may act against a wide variety of lesions. The importance of such a protective role is illustrated by the observation that, under conditions known to cause oxidative damage to cytoplasmic components, PNPase-deficient cells are less viable than wild-type cells. Further, when challenged with H2O2, PNPase-deficient cells accumulate 8-oxoG in cellular RNA to a greater extent than wild-type cells, suggesting that this RNase functions in minimizing oxidized RNA in vivo. Introducing the pnp gene encoding PNPase rescues defects in growth and RNA quality of the pnp mutant cells. Our results also suggest that protection against oxidative stress is an intrinsic function of PNPase because association with the RNA degradosome or with RNA helicase B (RhlB) is not required.
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影响因子：
4.8
作者：
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通讯作者：
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