X-ray crystallography of maturation and aminoacylation of transfer RNA

我们解决了几种参与tRNA成熟和转录后修饰的酶的晶体结构及其与tRNA的复合物。在加工步骤中，RNase PH对3'延伸的尾部序列进行修剪，如果RNase PH修剪掉tRNA的部分氨基酸附着的CCA末端，则CCA添加酶（模板非依赖性RNA聚合酶）修复CCA序列。Aquifex aeolicus RNase （PH在2.3 Å分辨率下）的晶体结构揭示了两个酶家族如何在没有任何核酸模板的帮助下进化到聚合定义的CCA三核苷酸。在转录后修饰过程中，与tRNA复合物中的古苷tRNA鸟嘌呤转糖基酶的晶体结构（3.3 Å分辨率）揭示了该酶如何通过将典型tRNA的l形变形为1形来识别和修饰深埋的核苷酸。tRNA（gm18）甲基转移酶的1.85 Å-resolution晶体结构揭示了在催化褶中发现的深结结构不仅构建了活性位点和辅因子结合位点，而且通过分子二聚化促进了rna依赖的甲基化机制。对于氨酰- trna合成酶，我们通过晶体学分析阐明了人类色氨酸- trna合成酶细胞因子活性的结构基础，这是该酶在漫长的进化过程中获得的。

We solved crystal structures of several enzymes involved in tRNA maturation and post-transcriptional modification and their complex with tRNA. In the processing step, 3'-extended trailer sequence is trimmed by RNase PH, and, if RNase PH trims off a part of the amino-acid-attaching CCA terminus of tRNA, then CCA-adding enzyme (template-independent RNA polymerase) repairs the CCA sequence. Crystal structure of Aquifex aeolicus RNase PH at 2.3 Å resolution) reveals how two enzyme families have evolved to polymerize defined CCA trinucleotides without aid of any nucleic-acid template. In the post-transcriptional modification process, crystal structure (3.3 Å resolution) of archaeosine tRNA guanine transglycosylase in a complex with tRNA uncovered how the enzyme recognizes and modifies a deeply-buried nucleotide by deformation of canonical tRNA L-shape to 1 -shape. The 1.85 Å-resolution crystal structure of tRNA(gm18)methyltransferase revealed that the deep knot structure found in the catalytic fold not only constructs active-site and cofactor-binding site but also facilitates RNA-dependent methylation mechanism via molecular dimerization. For aminoacyl-tRNA synthetase, we elucidated the structural basis for the cytokine activity of human tryptophanyl-tRNA synthetase by crystallographic analysis, which has been gained in the long evolution of the enzyme.