The Heat Shock Factor A4A Confers Salt Tolerance and Is Regulated by Oxidative Stress and the Mitogen-Activated Protein Kinases MPK3 and MPK6      . Issue 1 (27th March 2014)

• Record Type: Journal Article
• Authors: Pérez-Salamó, Imma; Papdi, Csaba; Rigó, Gábor; Zsigmond, Laura; Vilela, Belmiro; Lumbreras, Victoria; Nagy, István; Horváth, Balázs; Domoki, Mónika; Darula, Zsuzsa; Medzihradszky, Katalin; Bögre, László; Koncz, Csaba; Szabados, László
• Is Part Of: Plant physiology. Volume 165:Issue 1(2014)
• Page Start: 319
• Page End: 334
• Publication Date: 2014-03-27
• Subjects: Plant physiology -- Periodicals; Botany -- Periodicals; Periodicals; Electronic journals; 571.2
• DOI: 10.1104/pp.114.237891
• Languages: English
• ISSNs: 0032-0889

Abstract

Abstract : An Arabidopsis Heat Shock Factor affects tolerance to salt as well as other abiotic stresses, forms homodimers dependent on the redox regulation, interacts with MAP kinases, and alters the expression of a large set of stress-induced genes . Abstract: Heat shock factors (HSFs) are principal regulators of plant responses to several abiotic stresses. Here, we show that estradiol-dependent 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.