| Budget Amount *help |
¥15,660,000 (Direct Cost: ¥14,400,000、Indirect Cost: ¥1,260,000)
Fiscal Year 2007: ¥5,460,000 (Direct Cost: ¥4,200,000、Indirect Cost: ¥1,260,000)
Fiscal Year 2006: ¥4,900,000 (Direct Cost: ¥4,900,000)
Fiscal Year 2005: ¥5,300,000 (Direct Cost: ¥5,300,000)
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| Research Abstract |
Proteins associate and collaborate with RNAs to form ribonucleoproteins, which act in highly specific genetic information transfer process. In this study, we first focused on tRNA processing and post-translational modification. We solved the crystal structures of CCA-adding enzymes complexed with tRNA primer at each reaction step (Nature, 2006), MnmA thiouridine synthetase complexed with tRNA in three reaction steps (Nature, 2006), and TilS lysidine synthetase complexed with tRNA^<Ile2> (Nature, 2009) and revealed their dynamic RNA recognition and catalytic mechanism at an atomic resolution. Second, in eukarya and archaea, tRNA modifying and activating enzymes form channeling ribonucleoprotein complex with their cognate tRNA to fulfil the complex sequential chemical reactions. We solved the crystal structure of tRNA-dependent amidotransferase GatDE in a complex with tRNAGIn to show how the complex catalyzes three sequential reactions (Science, 2006). We further solved the crystal strictures of 3 out of 5 enzymes involved in synthesis of yW hypermodification in position 37 of eukaryotic and archaeal tRNA^<Phe> (J.Mol.Biol., 2008 ; Nucleic Acids Res., 2009 ; Proc.Natl.Acad.Sci.USA, 2009). These studies revealed how each enzyme utilizes S-adenosyl-methionine cofactor in different way to achieve the sequential modification reaction. Finally, we solved the crystal structure as well as biochemical analysis of Sec translocon machinery, acting in translocation of thus synthesized protein in cytoplasm across the membrane (Nature, 2009). We thus showed that SecYE channel and SecA molecular motor mutually transit their conformation from closed to open form to activate each other to achieve the protein translocation.
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