The Arabidopsis STRESS RESPONSE SUPPRESSOR DEAD-box RNA helicases are nucleolar- and chromocenter-localized proteins that undergo stress-mediated relocalization and are involved in epigenetic gene silencing

Asif Khan, Anna Garbelli, Serena Grossi, Assa Florentin, Giorgia Batelli, Tania Acuna, Gaston Zolla, Yuval Kaye, Laju K. Paul, Jian Kang Zhu, Giovanni Maga, Gideon Grafi, Simon Barak

Research output: Contribution to journalArticlepeer-review

52 Scopus citations

Abstract

DEAD-box RNA helicases are involved in many aspects of RNA metabolism and in diverse biological processes in plants. Arabidopsis thaliana mutants of two DEAD-box RNA helicases, STRESS RESPONSE SUPPRESSOR1 (STRS1) and STRS2 were previously shown to exhibit tolerance to abiotic stresses and up-regulated stress-responsive gene expression. Here, we show that Arabidopsis STRS-overexpressing lines displayed a less tolerant phenotype and reduced expression of stress-induced genes confirming the STRSs as attenuators of Arabidopsis stress responses. GFP-STRS fusion proteins exhibited localization to the nucleolus, nucleoplasm and chromocenters and exhibited relocalization in response to abscisic acid (ABA) treatment and various stresses. This relocalization was reversed when stress treatments were removed. The STRS proteins displayed mis-localization in specific gene-silencing mutants and exhibited RNA-dependent ATPase and RNA-unwinding activities. In particular, STRS2 showed mis-localization in three out of four mutants of the RNA-directed DNA methylation (RdDM) pathway while STRS1 was mis-localized in the hd2c mutant that is defective in histone deacetylase activity. Furthermore, heterochromatic RdDM target loci displayed reduced DNA methylation and increased expression in the strs mutants. Taken together, our findings suggest that the STRS proteins are involved in epigenetic silencing of gene expression to bring about suppression of the Arabidopsis stress response.

Original languageEnglish
Pages (from-to)28-43
Number of pages16
JournalPlant Journal
Volume79
Issue number1
DOIs
StatePublished - 1 Jan 2014

Keywords

  • Arabidopsis thaliana
  • DEAD-box RNA helicase
  • RNA-directed DNA methylation
  • abiotic stress response
  • epigenetic gene silencing
  • nucleolus

ASJC Scopus subject areas

  • Genetics
  • Plant Science
  • Cell Biology

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