2002 Fiscal Year Final Research Report Summary
Activation of plastid-localized latent polyphenol oxidase by autophagy induced by sucrose-starvation
| Project/Area Number |
12640630
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
植物生理
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| Research Institution | Shinshu University |
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Principal Investigator |
NOZUE Masayuki Shinshu University, Faculty of Textile Science and Technology, Associate professor, 繊維学部, 助教授 (30135165)
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| Co-Investigator(Kenkyū-buntansha) |
SAITO Hideki Shinshu University, Faculty of Textile Science and Technology, Lecturer, 繊維学部, 講師 (30021174)
KOJIMA Mineo Shinshu University, Faculty of Textile Science and Technology, Professor, 繊維学部, 教授 (30023469)
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| Project Period (FY) |
2000 – 2002
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| Keywords | Autophagy / Vacuole / cysteine endopeptidase / plastid / polyphenol oxidase / Ipomoea batatas / cell culture / proteolysis |
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| Research Abstract |
Polyphenol oxidase (PPO) that is translated as precursor protein in cytoplasm, then transported and localized in plastids as a latent form. However, PPO's substrates are localized in the other compartment (vacuoles). Plant PPO is well known as one of the most popular enzymes that are involved in browning of the injured or diseased tissues. However, its biological function in the living plant cell is not clear. In the present study, we demonstrate that the plastid-localized latent PPO is most probably activated by proteolytic cleavage involved in autophagy. Main experimental results are shown as follows.
1) We cloned 2 PPO isoform cDNAs from sweet potato cells.
2) Expression of PPO was induced by cell transfer to fresh medium, cell proliferation and treatment with methyl jasmonate.
3) Latent PPO was activated by proteolytic cleavage in the cells by sucrose starvation or methyl jasmonate.
4) A vacuole-localized cysteine endopeptidase (PPOase) that can cleave the latent PPO was partially purified. PPOase showed a high substrate specificity for PPO.
5) Proteolytic cleavage of latent PPO in the sweet potato cells that had been cultured in sucrose-deleted medium was markedly inhibited by E-64 or 3-methyladenine. Plastid number severely decrease by sucrose starvation, but both E-64 and 3-methyladenine also inhibited the breakdown of plastids.
6) Vacuoles were isolated from E-64 treated cells that had been cultured in sucrose-deleted medium. The vacuoles containing many DAPI-stained structures that seemed to be plastids were observed under fluorescent microscopy.
These experimental results indicate that autophagy is induced by sucrose starvation in sweet potato cells, and the active PPO is generated by proteolytic cleavage of the plastid-localized latent PPO involved in cysteine endopeptidase in the vacuoles.
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[Publications] Xu, W., Moriya, K., Yamada, K., Mishimura, M., Shioiri, H., Kojima, M., Nozue, M.: "Detection and characterization of a 36-kDa peptide in C-terminal region of a 24-kDa vacuolar protein (VP24) precursor in anthocyanin-producing sweet potato cells in suspension culture"Plant Science. 160. 121-128 (2000)
Description
「研究成果報告書概要(和文)」より
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[Publications] Nozue, M., Cai W., Li, L., Xu, W., Shioiri H., Kojima, M., Saito, H.: "Development of a reliable method for Agrobacterium tumefaciens-mediated traansformation of mulberry callus"Journal of Sericultural Science of Japan. 69. 345-352 (2000)
Description
「研究成果報告書概要(和文)」より
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[Publications] Xu, W., Moriya, K., Yamada, K., Kondo, M., Nishimura, M., Shioiri, H., Kojima, M., Nozue, M.: "Expression and localization of a 36-kDa peptide delived from a 24-kDa vacuolar protein (VP24) precursor in anthocyanin-producing sweet potato cells in suspension culture"Plant Biotechnology. 18. 203-208 (2001)
Description
「研究成果報告書概要(和文)」より
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[Publications] Nozue, M., Baba, S., Kitamura, Y., Xu, W., Kobu, H., Nogawa, M., Shioiri, H., Kojima, M.: "VP24 found in anthocyanic vacuolar inclusions(AVIs)of sweet potato cells is a member of a metalloprotease family"Biochemical Engineering Journal. 14. 199-205 (2003)
Description
「研究成果報告書概要(和文)」より
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[Publications] Nozue, M., Nakano, Y., Yoshida, Y., Shioiri, H., Kojima, M.: "Activation of polyphenol oxidase in sweetpotato cells in suspension culture"Twelfth Symposium of the International Society for Tropical Root Crops (ISTRC). Potential of root crops for food and industrial resources.(Eds. by Nakatani, M., Komaki, K.). 611 (2002)
Description
「研究成果報告書概要(和文)」より
-
[Publications] Xu, W., Moriya, K., Yamada, K., Nishimura, M., Shioiri, H., Kojima, M. and Nozue, M.: "Detection and characterization of a 36-kDa peptide in C-terminal region of a 24-kDa vacuolar protein (VP24) precursor in anthocyanin-producing sweet potato cells in suspension culture."Plant Science. 160. 121-128 (2000)
Description
「研究成果報告書概要(欧文)」より
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[Publications] Nozue, M., Cai W., Li, L., Xu, W., Shioiri, H., Kojima, M. and Saito, H.: "Development of a reliable method for Agrobacterum tumefaciens-mediated transformation of mulberry callus."Journal of Sericultural Science of Japan. 69. 345-352 (2000)
Description
「研究成果報告書概要(欧文)」より
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[Publications] Nozue, M., Baba, S., Kitamura Y., Xu, W., Kubo, H., Nogawa, M., Shioiri, H, and Kojima, M.: "VP24 found in anthocyanic vacuolar inclusions (AVIs) of sweet potato cells is a member of a metalloprotease family."Biochemical Engineering Journal. 14. 199-205 (2003)
Description
「研究成果報告書概要(欧文)」より
-
[Publications] Nozue, M., Nakano, Y., Yoshida, Y., Shioiri, H. and Kojima, M.: "Activation of polyphenol oxidase in sweetpotato cells in suspension culture."Twelfth Symposium of the International Society for Tropical Root Crops (ISTRC). Potential of root crops for food and industrial resources. Eds. by Nakatani, M. and Komaki, K.. 611 (2002)
Description
「研究成果報告書概要(欧文)」より
