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.
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.
French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, 84990, Israel.
Asif
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Khan
Anna
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Garbelli
Serena
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Grossi
Assa
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Florentin
Giorgia
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Batelli
Tania
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Acuna
Gaston
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Zolla
Yuval
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Kaye
Laju K
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Paul
Jian-Kang
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Zhu
Giovanni
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Maga
Gideon
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Grafi
Simon
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Barak
D000040:Abscisic Acid / Q000494:pharmacology; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002466:Cell Nucleolus / Q000378:metabolism; D032461:Chromosomes, Plant / Q000235:genetics; D053487:DEAD-box RNA Helicases / Q000235:genetics* / Q000378:metabolism; D019175:DNA Methylation; D035264:Flowers / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D018525:Germination; D009154:Mutation; D010641:Phenotype; D010937:Plant Growth Regulators / Q000494:pharmacology; D018515:Plant Leaves / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified; D021381:Protein Transport; D011993:Recombinant Fusion Proteins; D036226:Seedlings / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D012639:Seeds / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological
D029681:Arabidopsis Proteins; D010937:Plant Growth Regulators; D011993:Recombinant Fusion Proteins; D012965:Sodium Chloride; D000040:Abscisic Acid; C525658:STRS1 protein, Arabidopsis; C525659:STRS2 protein, Arabidopsis; D000251:Adenosine Triphosphatases; C027900:RNA-dependent ATPase; D053487:DEAD-box RNA Helicases
Arabidopsis thaliana; DEAD-box RNA helicase; RNA-directed DNA methylation; abiotic stress response; epigenetic gene silencing; nucleolus