Elucidation of the molecular mechanism of the enzyme Thg1 which catalyzes template-dependent RNA chain elongation in the 3'- 5'direction

2014 Fiscal Year Final Research Report

• Project/Area Number: 24370042
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Structural biochemistry
• Research Institution: Hokkaido University
• Principal Investigator: TANAKA Isao 北海道大学, 先端生命科学研究科(研究院), 特任教授 (70093052)
• Co-Investigator(Kenkyū-buntansha): YAO Min 北海道大学, 大学院先端生命科学研究院, 教授 (40311518)
• Co-Investigator(Renkei-kenkyūsha): KOMODA Keisuke 東京大学, 大学院農学生命科学研究科, 特任助教 (40581640)
• Research Collaborator: NAKAMURA Akiyoshi ; KIMURA Shoko
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: X線結晶構造解析 / tRNA修飾 / アミノアシル合成酵素 / グアニン転移酵素 / 岡崎フラグメント / 鋳型依存伸長反応 / 逆向き重合

Outline of Final Research Achievements

The structure analysis of the complex of Thg1 from eukaryote which catalyzes G-1 addition of tRNA(His) in template-independent manner, with tRNA(His) revealed that tetrameric Thg1 binds to two tRNA(His) molecules by recognizing CCA terminus and anticodon region, and that tRNA chain accesses to the reaction site from the opposite direction to that of DNA/RNA polymerase. Subsequent analysis of the complex of prokaryote Thg1 which catalyzes template-dependent nucleotide addition reaction, with tRNA(Phe) revealed that the Thg1 recognizes the shoulder region of the tRNA rather than the anticodon region, and that this binding mode is changed to that for the G-1 addition reaction when the anticodon is changed to that of tRNA(His). Furthermore, when GTP homologue (GDPNP) was inserted in the reaction site, the inserted base formed the Watson-Crick base pair with the tRNA base, while the 5' end of the tRNA chain moved and resulted in the formation of the structure for the extension reaction.

Free Research Field

X線結晶学，構造生物学