Ubiquitin-Proteasome Dependent Regulation of the GOLDEN2-LIKE 1 Transcription Factor in Response to Plastid Signals

Plant Physiol. 2017 Jan;173(1):524-535. doi: 10.1104/pp.16.01546. Epub 2016 Nov 7.


Arabidopsis (Arabidopsis thaliana) GOLDEN2-LIKE (GLK) transcription factors promote chloroplast biogenesis by regulating the expression of photosynthesis-related genes. Arabidopsis GLK1 is also known to participate in retrograde signaling from chloroplasts to the nucleus. To elucidate the mechanism by which GLK1 is regulated in response to plastid signals, we biochemically characterized Arabidopsis GLK1 protein. Expression analysis of GLK1 protein indicated that GLK1 accumulates in aerial tissues. Both tissue-specific and Suc-dependent accumulation of GLK1 were regulated primarily at the transcriptional level. In contrast, norflurazon- or lincomycin-treated gun1-101 mutant expressing normal levels of GLK1 mRNA failed to accumulate GLK1 protein, suggesting that plastid signals directly regulate the accumulation of GLK1 protein in a GUN1-independent manner. Treatment of the glk1glk2 mutant expressing functional GFP-GLK1 with a proteasome inhibitor, MG-132, induced the accumulation of polyubiquitinated GFP-GLK1. Furthermore, the level of endogenous GLK1 in plants with damaged plastids was partially restored when those plants were treated with MG-132. Collectively, these data indicate that the ubiquitin-proteasome system participates in the degradation of Arabidopsis GLK1 in response to plastid signals.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / drug effects
  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Cell Nucleus / metabolism
  • DNA-Binding Proteins / metabolism
  • Gene Expression Regulation, Plant
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Leupeptins / pharmacology
  • Plants, Genetically Modified
  • Plastids / metabolism*
  • Proteasome Endopeptidase Complex / metabolism
  • Proteasome Inhibitors / pharmacology
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Ubiquitin / metabolism*


  • Arabidopsis Proteins
  • DNA-Binding Proteins
  • GLK1 protein, Arabidopsis
  • GUN1 protein, Arabidopsis
  • Leupeptins
  • Proteasome Inhibitors
  • Transcription Factors
  • Ubiquitin
  • Green Fluorescent Proteins
  • Proteasome Endopeptidase Complex
  • benzyloxycarbonylleucyl-leucyl-leucine aldehyde