title: The heat shock factor A4A confers salt tolerance and is regulated by oxidative stress and the mitogen-activated protein kinases MPK3 and MPK6.
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.
authors.affiliation: Biological Research Centre, H-6726 Szeged, Hungary.
authors.forename: Imma
authors.initials: I
authors.lastname: Pérez-Salamó
authors.forename: Csaba
authors.initials: C
authors.lastname: Papdi
authors.forename: Gábor
authors.initials: G
authors.lastname: Rigó
authors.forename: Laura
authors.initials: L
authors.lastname: Zsigmond
authors.forename: Belmiro
authors.initials: B
authors.lastname: Vilela
authors.forename: Victoria
authors.initials: V
authors.lastname: Lumbreras
authors.forename: István
authors.initials: I
authors.lastname: Nagy
authors.forename: Balázs
authors.initials: B
authors.lastname: Horváth
authors.forename: Mónika
authors.initials: M
authors.lastname: Domoki
authors.forename: Zsuzsa
authors.initials: Z
authors.lastname: Darula
authors.forename: Katalin
authors.initials: K
authors.lastname: Medzihradszky
authors.forename: László
authors.initials: L
authors.lastname: Bögre
authors.forename: Csaba
authors.initials: C
authors.lastname: Koncz
authors.forename: László
authors.initials: L
authors.lastname: Szabados
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D004269:DNA, Bacterial / Q000235:genetics; D004958:Estradiol / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional / Q000235:genetics; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics; D010766:Phosphorylation / Q000187:drug effects; D030821:Plants, Genetically Modified; D011485:Protein Binding / Q000187:drug effects; D055503:Protein Multimerization / Q000187:drug effects; D054712:Salinity; D055049:Salt Tolerance / Q000187:drug effects / Q000235:genetics; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D014170:Transformation, Genetic / Q000187:drug effects
chemical_list: D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; C000593854:HSFA4A protein, Arabidopsis; C036483:T-DNA; D014157:Transcription Factors; D012965:Sodium Chloride; D004958:Estradiol; C458516:AtMPK3 protein, Arabidopsis; C436293:MPK6 protein, Arabidopsis; D020928:Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases