A non canonical subtilase attenuates the transcriptional activation of defence responses in Arabidopsis thaliana

Elife. 2016 Sep 29:5:e19755. doi: 10.7554/eLife.19755.

Abstract

Proteases play crucial physiological functions in all organisms by controlling the lifetime of proteins. Here, we identified an atypical protease of the subtilase family [SBT5.2(b)] that attenuates the transcriptional activation of plant defence independently of its protease activity. The SBT5.2 gene produces two distinct transcripts encoding a canonical secreted subtilase [SBT5.2(a)] and an intracellular protein [SBT5.2(b)]. Concomitant to SBT5.2(a) downregulation, SBT5.2(b) expression is induced after bacterial inoculation. SBT5.2(b) localizes to endosomes where it interacts with and retains the defence-related transcription factor MYB30. Nuclear exclusion of MYB30 results in its reduced transcriptional activation and, thus, suppressed resistance. sbt5.2 mutants, with abolished SBT5.2(a) and SBT5.2(b) expression, display enhanced defence that is suppressed in a myb30 mutant background. Moreover, overexpression of SBT5.2(b), but not SBT5.2(a), in sbt5.2 plants reverts the phenotypes displayed by sbt5.2 mutants. Overall, we uncover a regulatory mode of the transcriptional activation of defence responses previously undescribed in eukaryotes.

Keywords: A. thaliana; alternative splicing; hypersensitive response; plant biology; plant defence; subtilase; transcription factors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics*
  • Arabidopsis / immunology*
  • Arabidopsis Proteins / metabolism*
  • Endoplasmic Reticulum / metabolism
  • Gene Expression Regulation, Plant*
  • Protein Binding
  • Subtilisins / genetics
  • Subtilisins / metabolism*
  • Transcription Factors / metabolism
  • Transcriptional Activation*

Substances

  • Arabidopsis Proteins
  • MYB30 protein, Arabidopsis
  • Transcription Factors
  • Subtilisins
  • subtilase, plant

Grants and funding

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.