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首页> 外文期刊>Biochemistry >The 5' Leader of Precursor tRNA~(Asp)Bound to the Bacillus subtilis RNase P Holoenzyme Has an Extended Conformation
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The 5' Leader of Precursor tRNA~(Asp)Bound to the Bacillus subtilis RNase P Holoenzyme Has an Extended Conformation

机译：绑定到枯草芽孢杆菌RNase P全酶的前体tRNA〜（Asp）的5'领导者具有扩展的构象。

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摘要

RNase P catalyzes the 5' maturation of transfer RNA(tRNA).RNase P from Bacillus subtilis comprises a large RNA component(130 kDa,P RNA)and a small protein subunit(14 kDa,P protein).Although P RNA alone can efficiently catalyze the maturation reaction in vitro,P protein is strictly required under physiological conditions.We have used time-resolved fluorescence resonance energy transfer on a series of donor-labeled substrates and two acceptor-labeled P proteins to determine the conformation of the pre-tRNA 5' leader relative to the protein in the holoenzyme-pre-tRNA complex.The resulting distance distribution measurements indicate that the leader binds to the holoenzyme in an extended conformation between nucleotides 3 and 7.The conformational mobility of nucleotides 5-8 in the leader is reduced,providing further evidence that these nucleotides interact with the holoenzyme.The increased fluorescence intensity and lifetime of the 5'-fluorescein label of these leaders indicate a more hydrophobic environment,consistent with the notion that such interactions occur with the central cleft of the P protein.Taken together,our data support a model where the P protein binds to the 5' leader between the fourth and seventh nucleotides upstream of the cleavage site,extending the leader and decreasing its structural dynamics.Thus,P protein acts as a wedge to separate the 5' from the 3' terminus of the pre-tRNA and to position the cleavage site in the catalytic core.These results reveal a structural basis for the P protein dependent discrimination between precursor and mature tRNAs.
机译：RNase P催化转移RNA（tRNA）的5'成熟。枯草芽孢杆菌的RNase P包含一个较大的RNA成分（130 kDa，P RNA）和一个小的蛋白质亚基（14 kDa，P蛋白质）。在体外催化成熟反应，在生理条件下严格要求P蛋白。我们使用时间分辨的荧光共振能量转移在一系列供体标记的底物和两个受体标记的P蛋白上确定pre-tRNA的构象相对于完整酶-pre-tRNA复合物中蛋白质的5'前导序列。距离测量结果表明前导序列以核苷酸3和7之间的扩展构象与完整酶结合。前导核苷酸5-8的构象迁移率减少，提供了进一步的证据表明这些核苷酸与全酶相互作用。这些前导序列的5'-荧光素标记的荧光强度增强和寿命增加，表明其亲水性更高。恐怖的环境，与这种相互作用与P蛋白的中央裂口发生的观点一致。我们的数据合在一起支持了一个模型，其中P蛋白与切割位点上游第四和第七个核苷酸之间的5'前导序列结合，因此，P蛋白充当楔形物将pre-tRNA的5'与3'末端分开，并将裂解位点定位在催化核心中，这些结果揭示了P的结构基础前体和成熟tRNA之间的P蛋白依赖性区分。

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