Journal Article

The Heat Shock Factor A4A Confers Salt Tolerance and Is Regulated by Oxidative Stress and the Mitogen-Activated Protein Kinases MPK3 and MPK6

Darula, Zsuzsa, Bögre, László, Koncz, Csaba, Domoki, Mónika, Lumbreras, Victoria, Szabados, László, Papdi, Csaba, Medzihradszky, Katalin, Rigo, Gábor, Vilela, Belmiro, Pérez-Salamó, Imma, Zsigmond, Laura, Nagy, István, Horváth, Balázs

2014

Overview

Heat shock factors (HSFs) are principal regulators of plant responses to several abiotic stresses. Here, we show that estradioldependent induction of HSFA4A confers enhanced tolerance to salt and oxidative agents, whereas inactivation of HSFA4A results in hypersensitivity to salt stress in Arabidopsis (Arabidopsis thaliana). Estradiol induction of HSFA4A in transgenic plants decreases, while the knockout hsfa4a mutation elevates hydrogen peroxide accumulation and lipid peroxidation. Overexpression of HSFA4A alters the transcription of a large set of genes regulated by oxidative stress. In yeast (Saccharomyces cerevisiae) two-hybrid and bimolecular fluorescence complementation assays, HSFA4A shows homomeric interaction, which is reduced by alanine replacement of three conserved cysteine residues. HSFA4A interacts with mitogen-activated protein kinases MPK3 and MPK6 in yeast and plant cells. MPK3 and MPK6 phosphorylate HSFA4A in vitro on three distinct sites, serine-309 being the major phosphorylation site. Activation of the MPK3 and MPK6 mitogen-activated protein kinase pathway led to the transcriptional activation of the HEAT SHOCK PROTEIN17.6A gene. In agreement that mutation of serine-309 to alanine strongly diminished phosphorylation of HSFA4A, it also strongly reduced the transcriptional activation of HEAT SHOCK PROTEIN17.6A. These data suggest that HSFA4A is a substrate of the MPK3/MPK6 signaling and that it regulates stress responses in Arabidopsis.

• Publisher: American Society of Plant Biologists
• Subject: abiotic stress / Amino Acid Sequence / Arabidopsis / Arabidopsis - enzymology / Arabidopsis - genetics / Arabidopsis - growth & development / Arabidopsis - physiology / Arabidopsis Proteins - chemistry / Arabidopsis Proteins - genetics / Arabidopsis Proteins - metabolism / Cell culture techniques / Cell Nucleus - drug effects / Cell Nucleus - metabolism / Cells, Cultured / DNA, Bacterial - genetics / Estradiol - pharmacology / Gene Expression Regulation, Plant - drug effects / Genes / Genes, Plant / heat shock proteins / Heat stress disorders / mitogen-activated protein kinase / Mitogen-Activated Protein Kinase Kinases - metabolism / Mitogen-Activated Protein Kinases - metabolism / Molecular Sequence Data / Mutagenesis, Insertional - genetics / Oxidation-Reduction - drug effects / Oxidative stress / Oxidative Stress - drug effects / Oxidative Stress - genetics / Phosphorylation / Phosphorylation - drug effects / Plant cells / Plants / Plants, Genetically Modified / Protein Binding - drug effects / Protein Multimerization - drug effects / Salinity / Salt tolerance / Salt Tolerance - drug effects / Salt Tolerance - genetics / Shock heating / SIGNALING AND RESPONSE / Sodium Chloride - pharmacology / Stress, Physiological - drug effects / Stress, Physiological - genetics / Transcription factors / Transcription Factors - chemistry / Transcription Factors - genetics / Transcription Factors - metabolism / Transcription, Genetic - drug effects / Transformation, Genetic - drug effects