Journal Article

Activation of the Promoters of Arabidopsis Genes for the Branched-Chain α-Keto Acid Dehydrogenase Complex in Transgenic Tobacco BY-2 Cells under Sugar Starvation

Yuki Fujiki, Masaki Ito, Takashi Itoh, Ikuo Nishida and Akira Watanabe

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 43, issue 3, pages 275-280
Published in print March 2002 | ISSN: 0032-0781
Published online March 2002 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcf032
Activation of the Promoters of Arabidopsis Genes for the Branched-Chain α-Keto Acid Dehydrogenase Complex in Transgenic Tobacco BY-2 Cells under Sugar Starvation

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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Sugar starvation exerted by sub-10 mM levels of sucrose on Arabidopsis T87 suspension-cultured cells triggered marked accumulation of the transcripts of genes for E1β and E2 subunit of the branched-chain α-keto acid dehydrogenase complex. Similar levels of sugar starvation increased the luciferase activity in transgenic tobacco BY-2 lines expressing the Arabidopsis E1β- or E2-promoter-luciferase fusion gene. These results indicate that sugar levels tightly regulate the E1β and E2 promoter activity in the heterologous plant system. We further showed in the transgenic tobacco BY-2 lines that sugar-starvation-induced activation of the E1β and E2 promoters was prevented by K-252a, an inhibitor of Ser/Thr protein kinase, and was enhanced by okadaic acid, an inhibitor of protein phosphatases. By contrast, the cauliflower mosaic virus 35S promoter activity in sugar-starved BY-2 cells was not significantly affected by K-252a and only slightly enhanced by okadaic acid. Taken together, we propose that transcriptional activation of genes for the branched-chain α-keto acid dehydrogenase complex and its modulation by specific protein kinases/phosphatases are of critical importance in branched-chain amino acid catabolism in plant cells under sugar starvation.

Keywords: Key words: Branched-chain α-keto acid dehydrogenase — Promoter — Protein kinase — Protein phosphatase — Sugar starvation.; Abbreviations: BCKDH, branched-chain α-keto acid dehydrogenase; CaMV, cauliflower mosaic virus; DMSO, dimethyl sulfoxide; LUC, luciferase.

Journal Article.  3850 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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