Characterization of the DNA-Mediated Oxidation of Dps, A Bacterial Ferritin.
Characterization of the DNA-Mediated Oxidation of Dps, A Bacterial Ferritin.
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DOI：
10.1021/jacs.6b06507
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发表时间：
2016-09-07
影响因子：
15
通讯作者：
Barton JK
中科院分区：
文献类型：
--
作者：
Arnold AR;Zhou A;Barton JK
Dps蛋白是保护DNA免受氧化应激的细菌铁蛋白，并与细菌的存活和毒力有关。除了通过扩散氧化剂直接氧化Dps铁位点之外，通过DNA电荷传输（CT）从远处氧化，其中电子和电子空穴通过碱基对π堆叠快速传输，可以代表Dps利用的有效DNA保护机制。在这里，我们的光谱特征的DNA介导的氧化亚铁负载的DP。X波段EPR用于监测DNA结合的Dps的氧化后，DNA光氧化使用嵌入钌光氧化剂和闪光淬灭技术。在用聚（dGdC）2照射后，g = 4.3的信号出现，与低对称性的单核高自旋Fe（III）位点的形成一致，所述低对称性的单核高自旋Fe（III）位点是Dps与每个铁氧化酶位点结合的预期氧化产物。当聚（dGdC）2被聚（dAdT）2取代时，Dps氧化的产率显着降低，与促进Dps氧化的鸟嘌呤自由基中间体一致。我们还探讨了可能的蛋白质电子转移（ET）的中间体在DNA介导的氧化亚铁载Dps。Dps蛋白含有一个保守的色氨酸残基，该残基紧邻铁结合铁氧化酶位点（E. coli Dps）。在EPR研究的氧化亚铁负载Dps的DNA光氧化后，W52A Dps突变体是显着不足相比，野生型Dps在形成的特征EPR信号在g = 4.3，W52作为ET跳跃中间一致。这种效应在E.大肠杆菌的存活率响应于过氧化氢，其中W52的突变导致在氧化应激下的存活率降低。
Dps proteins are bacterial ferritins that protect DNA from oxidative stress and have been implicated in bacterial survival and virulence. In addition to direct oxidation of the Dps iron sites by diffusing oxidants, oxidation from a distance via DNA charge transport (CT), where electrons and electron holes are rapidly transported through the base-pair π-stack, could represent an efficient DNA protection mechanism utilized by Dps. Here, we spectroscopically characterize the DNA-mediated oxidation of ferrous iron-loaded Dps. X-band EPR was used to monitor the oxidation of DNA-bound Dps after DNA photooxidation using an intercalating ruthenium photooxidant and the flash-quench technique. Upon irradiation with poly(dGdC)2, a signal arises with g = 4.3, consistent with the formation of mononuclear high-spin Fe(III) sites of low symmetry, the expected oxidation product of Dps with one iron bound at each ferroxidase site. When poly(dGdC)2 is substituted with poly(dAdT)2, the yield of Dps oxidation is decreased significantly, consistent with guanine radical intermediates facilitating Dps oxidation. We have also explored possible protein electron transfer (ET) intermediates in the DNA-mediated oxidation of ferrous iron-loaded Dps. Dps proteins contain a conserved tryptophan residue in close proximity to the iron-binding ferroxidase site (W52 in E. coli Dps). In EPR studies of the oxidation of ferrous iron-loaded Dps following DNA photooxidation, a W52A Dps mutant was significantly deficient compared to WT Dps in forming the characteristic EPR signal at g = 4.3, consistent with W52 acting as an ET hopping intermediate. This effect is mirrored in vivo in E. coli survival in response to hydrogen peroxide, where mutation of W52 leads to decreased survival under oxidative stress.
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影响因子：
2.9
作者：
Bou-Abdallah, F.;Yang, H.;Awomolo, A.;Cooper, B.;Woodhall, M. R.;Andrews, S. C.;Chasteen, N. D.
通讯作者：
Chasteen, N. D.
影响因子：
15
作者：
Grodick, Michael A.;Segal, Helen M.;Zwang, Theodore J.;Barton, Jacqueline K.
通讯作者：
Barton, Jacqueline K.
影响因子：
15
作者：
Arnold AR;Barton JK
通讯作者：
Barton JK
影响因子：
4.6
作者：
ANDERSON, PA;DEACON, GB;WHITE, AH
通讯作者：
WHITE, AH
影响因子：
3.6
作者：
Chodavarapu, Sundari;Gomez, Ruben;Kaguni, Jon M.
通讯作者：
Kaguni, Jon M.