Leucine and its keto acid enhance the coordinated expression of genes for branched‐chain amino acid catabolism in Arabidopsis under sugar starvation

FEBS Letters

Watanabe, Akira¹  Fujiki, Yuki¹  Ito, Masaki¹  Nishida, Ikuo¹ 

[1] Department of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, Hongo, Tokyo 113-0033, Japan

关键词: Branched-chain amino acid;    Branched-chain α-keto acid;    Hexokinase;    Sugar starvation;    Arabidopsis;    BCKDH;    branched-chain α-keto acid dehydrogenase;    Cab;    chlorophyll a/b binding protein;    DCMU;    3-(3;    4-dichlorophenyl)-1;    1-dimethylurea;    KIC;    α-ketoisocaproate;    NR;    nitrate reductase;    MCCase;    β-methylcrotonyl-coenzyme A carboxylase;   

DOI  :  10.1016/S0014-5793(01)02536-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Branched-chain α-keto acid dehydrogenase (BCKDH), a multienzyme complex, plays a key role in branched-chain amino acid catabolism. However, it remains unclear whether expression of each subunit is coordinately regulated in plants, which should be important for the efficient assembly of subunits into a functional multienzyme complex. We show that the transcripts from the Arabidopsis E1α subunit gene accumulated in dark-adapted leaves and in sugar-starved suspension cells. These results are complementary to our previous report that the transcripts for the E1β and E2 subunit genes accumulated in sugar-starved cells. Expression of the E1α gene is likely to be regulated by hexokinase-mediated sugar signaling, indicating that sugar plays a regulatory role in the coordinated expression of BCKDH subunit genes. Furthermore, Leu and its metabolite α-ketoisocaproate have synergistic effects on the enhanced expression of BCKDH subunit genes under sugar starvation. We hence suggest that branched-chain amino acids activate their own degradation pathway in sugar-starved cells through co-induction of each subunit gene of BCKDH.

【 授权许可】

Unknown