2018 Fiscal Year Final Research Report
Molecular mechanisms of nucleic acid-dependent stimulation of K63-linked polyubiquitylation
| Project/Area Number |
17K19344
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Molecular and Genome biology and related fields
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| Research Institution | National Institute of Genetics |
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Principal Investigator |
Kurokawa Yumiko 国立遺伝学研究所, 新分野創造センター, 特任研究員 (10381633)
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| Co-Investigator(Kenkyū-buntansha) |
松崎 由理 東京工業大学, リーダーシップ教育院, 特任准教授 (30572888)
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| Project Period (FY) |
2017-06-30 – 2019-03-31
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| Keywords | ubiquitin / K63 / DNA / RNA / 核酸 / ポリユビキチン / E2 / pH |
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| Outline of Final Research Achievements |
K63-linked polyubiquitin chain is known that it does not only stimulate the functional change of target proteins but also itself works as a signal of stress response, DNA damage, and so on. Although we believed that K63Ub chain formation must be up-regulated quickly/accurately in vivo, K63Ub chain formation by E2 enzyme Ubc13/Mms2 was slow reaction in vitro. To understand the molecular mechanism in up-regulation of K63Ub chain formation, we previously performed a screening assay for identifying factors which stimulates K63Ub chain reaction (without E3) and finally found that nucleic-acids (RNA and ssDNA) strongly promotes the E2-dependent K63Ub chain formation in vitro. In this study, we focused on the stimulatory mechanism of this reaction and we found that Ubc13/Mms2 heterodimer has nucleic-acid binding activity which is controlled by pH. E2-nucleic acid complex forms aggregate which seems to act as a K63Ub-assembly factory for chain extension.
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| Free Research Field |
ゲノム恒常性維持
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| Academic Significance and Societal Importance of the Research Achievements |
Ub鎖の形成促進は、これまでE3酵素によってのみ触媒されると考えられてきた。しかしE3がどのようなメカニズムでUb鎖の伸長を促進しているかの詳細は未解明の部分が多い。我々はK63Ub鎖伸長の活性本体であるE2に着目し、E2の活性を上昇するメカニズムを探索した。その結果、核酸が直接E2と結合し、構造体としてK63Ub鎖の形成を促進することを生化学解析や高速AFMを用いた１分子解析から明らかにした。反応メカニズムの解明はUb分野への貢献が大きく、pHによるタンパク質の活性制御は酵素学的にも意義が高い。DNA、RNAに関わる細胞内機構を中心に、pH変化による制御機構という新しい分野を見出した。
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