| Budget Amount *help |
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2020: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2019: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2018: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
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| Outline of Final Research Achievements |
In this study, the reaction mechanism of the ct6A-modifying enzyme TcdA was analyzed using mass spectrometry and radioisotopes. It was found that the sulfur atom withdrawn from cysteine by CsdA and CsdE is transferred to the t6A side chain to produce the thiocarboxylic form st6A. st6A is chemically unstable and spontaneously produces ct6A. We found that st6A is a novel modification that is also present in the cells. These findings significantly modify the previous ct6A biosynthesis model. The co-crystal structure of TcdA and tRNA allowed us to identify the residues important for the reaction. Stable isotope labeling experiments proved that the hydrolysis of ct6A actually occurs in the cell, indicating that the ct6A modification is truly reversible.
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