Structural and functional studies on biological macromolecules involved in the flow of genetic information and the cellular signal transduction.

为了详细了解由大分子相互作用级联组成的遗传表达和细胞信号转导系统，通过晶体学以原子分辨率分析了级联中涉及的分子相互作用。我们针对转录后tRNA加工和修饰酶和氨酰-tRNA合成酶，它们负责在翻译过程中准确连接tRNA和氨基酸，并对其与tRNA，其他底物和/或抑制剂的复合物进行结构分析。我们还确定了Vasa的晶体结构，RNA解旋酶参与果蝇生殖系的分化，并阐明了由DEAD盒RNA解旋酶的RNA双链解析的结构基础。此外，我们成功地确定了RNA聚合酶和Dmc 1的晶体结构，它们分别在转录和减数分裂中的同源重组中发挥核心作用。结构信息被应用于开发人工遗传密码系统，以将有用的、天然的或非天然的氨基酸整合到任何蛋白质的特定位置。我们已经建立了掺入酪氨酸或赖氨酸衍生物的系统，从而开辟了一条技术途径，该技术有助于掺入具有荧光、反应性或含重原子基团的氨基酸。

To understand in detail the systems of genetic expression and cellular signal transduction, which consist of cascades of macromolecular interactions, molecular interactions involved in the cascades were analyzed at atomic resolutions by crystallography. We targeted post-transcriptional tRNA processing and modification enzymes and aminoacyl-tRNA synthetases, which are responsible for accurate joining tRNA and amino acid during translation, and performed structural analyses of their complexes with tRNAs, other substrates, and/or inhibitors. We also determined the crystal structure of Vasa, an RNA helicase involved in the differentiation of Drosophila germline, and elucidated structural basis of the RNA double strand resolution by a DEAD-box RNA helicase. Furthermore, we succeeded in crystal structure determination of RNA polymerase and Dmc1, which play central roles in transcription and homologous recombination in meiosis, respectively. The structural information was applied to develop the artificial genetic code system to incorporate a useful, natural or non-natural amino acid into a specific position of any protein. We have established systems to incorporate tyrosine or lysine derivatives, and thus opened a way to the technology that facilitates incorporating an amino acid possessing fluorescent, reactive, or heavy-atom containing groups.