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Ubiquitin protein ligase 3 mediates the proteasomal degradation of GLABROUS 3 and ENHANCER OF GLABROUS 3, regulators of trichome development and flavonoid biosynthesis in A rabidopsis
Author(s) -
Patra Barunava,
Pattanaik Sitakanta,
Yuan Ling
Publication year - 2013
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12132
Subject(s) - ubiquitin ligase , proteasome , ubiquitin , bimolecular fluorescence complementation , microbiology and biotechnology , enhancer , proteolysis , transcription factor , f box protein , biology , ectopic expression , protein degradation , biochemistry , downregulation and upregulation , mutant , chemistry , gene , enzyme
Summary Ubiquitin/ 26 S proteasome ( UPS )‐dependent proteolysis of a variety of cellular proteins plays an essential role in many basic cellular processes. UPS impacts transcriptional regulation by controlling the stability, and thus the activity, of numerous transcription factors ( TF s). In Arabidopsis, trichome development and flavonoid metabolism are intimately connected, and several TF s have been identified that simultaneously control both processes. Here we show that UPS ‐dependent proteolysis of two of these TF s, GLABROUS 3 ( GL 3) and ENHANCER OF GL 3 ( EGL 3), is mediated by ubiquitin protein ligase 3 ( UPL 3). Cell‐free degradation and in planta stabilization assays in the presence of MG 132, an inhibitor of proteasome activity, demonstrated that the degradation of GL 3 and EGL 3 proteins is 26 S UPS ‐dependent. Yeast‐ or protoplast‐based two‐hybrid and bimolecular fluorescent complementation assays showed that GL 3 and EGL 3 interact via their C ‐terminal domains with the N ‐terminal portion of UPL 3. Moreover, both TF s are stabilized and show increased activities in a upl3 mutant background. Gene expression analyses revealed that UPL3 expression is negatively affected by mutation in the gl3 locus, but is moderately upregulated by the overexpression of GL3 , suggesting the presence of a regulatory loop involving GL 3 and UPL 3. Our findings underscore the importance of post‐translational controls in epidermal cell differentiation and flavonoid metabolism.