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首页> 外文期刊>Journal of Molecular Biology >Crystal structure of Dps-1, a functionally distinct Dps protein from Deinococcus radiodurans.
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Crystal structure of Dps-1, a functionally distinct Dps protein from Deinococcus radiodurans.

机译：Dps-1的晶体结构，这是一种功能不同的Dps蛋白，来自Deinococcus radiodurans。

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摘要

DNA protection during starvation (Dps) proteins play an important role in protecting cellular macromolecules from damage by reactive oxygen species (ROS). Unlike most orthologs that protect DNA by a combination of DNA binding and prevention of hydroxyl radical formation by ferroxidation and sequestration of iron, Dps-1 from the radiation-resistant Deinococcus radiodurans fails to protect DNA from hydroxyl radical-mediated cleavage through a mechanism inferred to involve continuous release of iron from the protein core. To address the structural basis for this unusual release of Fe(2+), the crystal structure of D. radiodurans Dps-1 was determined to 2.0 Angstroms resolution. Two of four strong anomalous signals per protein subunit correspond to metal-binding sites within an iron-uptake channel and a ferroxidase site, common features related to the canonical functions of Dps homologs. Similar to Lactobacillus lactis Dps, a metal-binding site is found at the N-terminal region. Unlike other metal sites, this site is located at the base of an N-terminal coil on the outer surface of the dodecameric protein sphere and does not involve symmetric association of protein subunits. Intriguingly, a unique channel-like structure is seen featuring a fourth metal coordination site that results from 3-fold symmetrical association of protein subunits through alpha2 helices. The presence of this metal-binding site suggests that it may define an iron-exit channel responsible for the continuous release of iron from the protein core. This interpretation is supported by substitution of residues involved in this ion coordination and the observation that the resultant mutant protein exhibits significantly attenuated iron release. Therefore, we propose that D. radiodurans Dps-1 has a distinct iron-exit channel.
机译：饥饿（Dps）蛋白中的DNA保护在保护细胞大分子免受活性氧（ROS）损害方面起着重要作用。与大多数直向同源物不同，直向同源物通过结合DNA结合和通过铁的铁氧化和螯合防止羟基自由基的形成来保护DNA，而抗辐射的Deinococcus radiodurans的Dps-1不能通过推断的机制保护DNA免受羟基自由基介导的裂解。涉及铁从蛋白质核心中连续释放。为了解决Fe（2+）这种异常释放的结构基础，确定了D. radiodurans Dps-1的晶体结构为2.0埃分辨率。每个蛋白质亚基的四个强异常信号中的两个对应于铁摄取通道和铁氧化酶位点内的金属结合位点，这些共同特征与Dps同源物的规范功能有关。与乳酸乳杆菌Dps相似，在N端区域发现了一个金属结合位点。与其他金属位点不同，此位点位于十二聚体蛋白质球外表面上的N末端线圈的基部，并且不涉及蛋白质亚基的对称缔合。有趣的是，看到了一个独特的通道状结构，其特征是第四个金属配位位点，该位点是由蛋白质亚基通过alpha2螺旋的3倍对称缔合产生的。该金属结合位点的存在表明它可能定义了铁释放通道，该通道负责铁从蛋白质核心中的连续释放。这种解释是通过取代参与该离子配位的残基和观察到的所得突变蛋白显示出显着减弱的铁释放来支持的。因此，我们建议D. radiodurans Dps-1具有一个独特的铁出口通道。

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