Contribution of dihydrouridine in folding of the D-arm in tRNA
Contribution of dihydrouridine in folding of the D-arm in tRNA
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DOI：
10.1039/c5ob00164a
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发表时间：
2015-01-01
影响因子：
3.2
通讯作者：
Lescrinier, E.
中科院分区：
文献类型：
--
作者：
Dyubankova, N.;Sochacka, E.;Lescrinier, E.
转移rna （tRNA）的转录后修饰被证明对tRNA功能的所有核心方面都至关重要。虽然大多数tRNA修饰是在20世纪70年代发现的，但它们在tRNA折叠、稳定性和解码中的作用往往是难以捉摸的。在这项工作中，进行了核磁共振研究，以获得更多关于二氢吡啶(D)修饰在S. pombe tRNA(i)(Met) D臂中的作用。虽然未修饰的寡核苷酸采用了几种在溶液中相互转换的未定义构象，但D核苷的存在引发折叠成具有稳定茎和柔性环区的发夹。显然，所研究的序列需要D修饰才能折叠成稳定的发夹。因此，我们认为D有助于tRNA中D臂的正确折叠和稳定性。与通常对核酸的假设相反，在90%的H2O中，在10ppm时，D核碱基的明显“极小”信号并不表明存在稳定的氢键。在修饰的核碱基中失去芳香特征后，pK(a)的强烈增加显着减慢了其“亚氨基”质子的交换，即使在90%的水中酸性到中性条件下也可以在分离的D核苷中观察到它。
Posttranscriptional modifications of transfer RNAs (tRNAs) are proven to be critical for all core aspects of tRNA function. While the majority of tRNA modifications were discovered in the 1970s, their contribution in tRNA folding, stability, and decoding often remains elusive. In this work an NMR study was performed to obtain more insight in the role of the dihydrouridine (D) modification in the D-arm of tRNA(i)(Met) from S. pombe. While the unmodified oligonucleotide adopted several undefined conformations that interconvert in solution, the presence of a D nucleoside triggered folding into a hairpin with a stable stem and flexible loop region. Apparently the D modification is required in the studied sequence to fold into a stable hairpin. Therefore we conclude that D contributes to the correct folding and stability of D-arm in tRNA. In contrast to what is generally assumed for nucleic acids, the sharp 'imino' signal for the D nucleobase at 10 ppm in 90% H2O is not indicative for the presence of a stable hydrogen bond. The strong increase in pK(a) upon loss of the aromatic character in the modified nucleobase slows down the exchange of its 'imino' proton significantly, allowing its observation even in an isolated D nucleoside in 90% H2O in acidic to neutral conditions.