The Red Light Receptor Phytochrome B Directly Enhances Substrate-E3 Ligase Interactions to Attenuate Ethylene Responses

Dev Cell. 2016 Dec 5;39(5):597-610. doi: 10.1016/j.devcel.2016.10.020. Epub 2016 Nov 23.

Abstract

Plants germinating under subterranean darkness assume skotomorphogenesis, a developmental program strengthened by ethylene in response to mechanical pressure of soil. Upon reaching the surface, light triggers a dramatic developmental transition termed de-etiolation that requires immediate termination of ethylene responses. Here, we report that light activation of photoreceptor phyB results in rapid degradation of EIN3, the master transcription factor in the ethylene signaling pathway. As a result, light rapidly and efficiently represses ethylene actions. Specifically, phyB directly interacts with EIN3 in a light-dependent manner and also physically associates with F box protein EBFs. The light-activated association of phyB, EIN3, and EBF1/EBF2 proteins stimulates robust EIN3 degradation by SCFEBF1/EBF2 E3 ligases. We reveal that phyB manipulates substrate-E3 ligase interactions in a light-dependent manner, thus directly controlling the stability of EIN3. Our findings illustrate a mechanistic model of how plants transduce light information to immediately turn off ethylene signaling for de-etiolation initiation.

Keywords: EBF1 and EBF2; EIN3; ethylene signaling; light signaling; photomorphogenesis; phytochrome B; seedling emergence; skotomorphogenesis.

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Arabidopsis Proteins / radiation effects
  • DNA-Binding Proteins
  • Ethylenes / metabolism*
  • F-Box Proteins / genetics
  • F-Box Proteins / metabolism*
  • Light
  • Models, Biological
  • Mutation
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Phototrophic Processes
  • Phytochrome B / metabolism*
  • Phytochrome B / radiation effects
  • Plants, Genetically Modified
  • Proteasome Endopeptidase Complex / metabolism
  • Protein Binding / radiation effects
  • Proteolysis / radiation effects
  • Signal Transduction
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism*

Substances

  • Arabidopsis Proteins
  • DNA-Binding Proteins
  • EBF1 protein, Arabidopsis
  • EBF2 protein, Arabidopsis
  • EIN3 protein, Arabidopsis
  • Ethylenes
  • F-Box Proteins
  • Nuclear Proteins
  • PHYB protein, Arabidopsis
  • Transcription Factors
  • Phytochrome B
  • ethylene
  • Ubiquitin-Protein Ligases
  • Proteasome Endopeptidase Complex
  • ATP dependent 26S protease