Arabidopsis E3 ubiquitin ligase PLANT U-BOX13 (PUB13) regulates chitin receptor LYSIN MOTIF RECEPTOR KINASE5 (LYK5) protein abundance

New Phytol. 2017 Jun;214(4):1646-1656. doi: 10.1111/nph.14472. Epub 2017 Feb 14.

Abstract

Long-chain chitooligosaccharides are fungal microbe-associated molecular patterns (MAMPs) that are recognized by LYSIN MOTIF RECEPTOR KINASE5 (LYK5), inducing the formation of a complex with CHITIN ELICITOR RECEPTOR KINASE1 (CERK1). Formation of this complex leads to activation of the CERK1 intracellular kinase domain and induction of plant innate immunity in Arabidopsis. We found that addition of chitooctaose induced LYK5 protein accumulation as a result of de novo gene expression and the inhibition of LYK5 protein degradation. Screening the putative E3 ligases for interaction with LYK5 identified PLANT U-BOX13 (PUB13), which complexed with LYK5, but this complex dissociated upon addition of chitooctaose. Consistent with these results, LYK5 protein abundance was higher in pub13 mutants compared with the wild type without chitooctaose treatment, while similar abundance was detected with the addition of chitooctaose. The pub13 mutants showed hypersensitivity to chitooctaose-induced rapid responses, such as the production of reactive oxygen species (ROS) and mitogen-activated protein (MAP) kinase phosphorylation, but exhibited normal responses to subsequent long-term chitooctaose treatment, such as gene expression and callose deposition. In addition, PUB13 could ubiquitinate the LYK5 kinase domain in vitro. Taken together, our results suggest an important regulatory function for the turnover of LYK5 mediated by the E3 ligase PUB13.

Keywords: CHITIN ELICITOR RECEPTOR KINASE1 (AtCERK1); E3 ligase; LYSIN MOTIF RECEPTOR KINASE5 (AtLYK5); PLANT U-BOX13 (AtPUB13); chitin; microbe-associated molecular pattern (MAMP)-triggered immunity; protein degradation; ubiquitination.

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Chitin / analogs & derivatives
  • Chitin / metabolism
  • Chitosan
  • Nicotiana / genetics
  • Oligosaccharides / metabolism
  • Pathogen-Associated Molecular Pattern Molecules / metabolism
  • Phylogeny
  • Plants, Genetically Modified
  • Protein Kinases / genetics
  • Protein Kinases / metabolism*
  • Proteolysis
  • Reactive Oxygen Species / metabolism
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism*
  • Ubiquitination

Substances

  • Arabidopsis Proteins
  • Oligosaccharides
  • Pathogen-Associated Molecular Pattern Molecules
  • Reactive Oxygen Species
  • chitooctaose
  • oligochitosan
  • Chitin
  • Chitosan
  • PUB13 protein, Arabidopsis
  • Ubiquitin-Protein Ligases
  • LYK5 protein, Arabidopsis
  • Protein Kinases