2023 Fiscal Year Final Research Report
Function of the new open reading frame appeared by cytoplasmic splicing in plants
| Project/Area Number |
20H02950
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Basic Section 38060:Applied molecular and cellular biology-related
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| Research Institution | Osaka Metropolitan University (2022-2023)
Osaka Prefecture University (2020-2021) |
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Principal Investigator |
Koizumi Nozomu 大阪公立大学, 大学院農学研究科, 教授 (20252835)
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Keywords | 小胞体ストレス応答 / シロイヌナズナ / 転写因子 / 細胞質スプライシング |
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| Outline of Final Research Achievements |
In the Arabidopsis ER stress response, cytoplasmic splicing converts bZIP60u to bZIP60s. bZIP60u contains a TMD and bZIP60s loses it, thereby bZIP60s translocates from the ER to the nucleus and acts as a transcription factor. In addition, bZIP60s acquires new ORF called ORF2. bZIP60s showed much higher transcriptional activity of BiP3 promoter than bZIP60 lacking ORF2. This result indicated that ORF2 has functions to enhance transcriptional activity of bZIP60s. This research aimed to clarify function of ORF2. We found that the NLS like sequence at the C-terminus of ORF2 and showed it to be a functional NLS using GFP. However, transcriptional activity bZIP60s lacking C-terminal NLS was lower than that of intact bZIP60s, the activity was still higher than that of bZIP60 lacking ORF2, indicating alternative mechanism. The enhanced activation capacity of bZIP60s was not dependent on the amount of protein. Thus, alterative mechanism may contribute to the activation capacity of bZIP60s.
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| Free Research Field |
農学
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| Academic Significance and Societal Importance of the Research Achievements |
真核生物は多くの転写因子を持つが、その活性化機構は多様である。小胞体ストレス応答におけるbZIP 型転写因子の活性化は細胞質スプライシングを介する非常にユニークなメカニズムによって起こる。特に興味深いのは酵母、ヒト、シロイヌナズナでは細胞質スプライシングで活性化される点では共通しているが、タンパク質の構造変化が大きく異なる点である。私たちはシロイヌナズナbZIP60の活性化に伴って新たな読み枠（ORF2）が生じることを明らかにしてきたが、その機能については全く不明であった。本研究ではORF2が転写活性化に非常に重要であることを明らかとするとともに、そのメカニズムについて多くの知見を得た。
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