The Heat Shock Factor A4A Confers Salt Tolerance and Is Regulated by Oxidative Stress and the Mitogen-Activated Protein Kinases MPK3 and MPK6
The Heat Shock Factor A4A Confers Salt Tolerance and Is Regulated by Oxidative Stress and the Mitogen-Activated Protein Kinases MPK3 and MPK6
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DOI：
10.1104/pp.114.237891
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发表时间：
2014-05-01
期刊：
影响因子：
7.4
通讯作者：
Szabados, Laszlo
中科院分区：
文献类型：
--
作者：
Perez-Salamo, Imma;Papdi, Csaba;Szabados, Laszlo
热休克因子（HSFs）是植物对多种非生物胁迫反应的主要调节因子。本研究表明，雌二醇依赖性诱导HSFA4A增强了拟南芥对盐和氧化剂的耐受性，而HSFA4A失活导致拟南芥对盐胁迫过敏。雌二醇诱导HSFA4A在转基因植物中降低，而敲除HSFA4A突变增加过氧化氢积累和脂质过氧化。HSFA4A的过表达改变了氧化应激调控的大量基因的转录。在酵母（Saccharomyces cerevisiae）的双杂交和双分子荧光互补实验中，HSFA4A表现出同源相互作用，通过丙氨酸取代三个保守的半胱氨酸残基而减少。HSFA4A在酵母和植物细胞中与丝裂原活化蛋白激酶MPK3和MPK6相互作用。MPK3和MPK6在体外三个不同的位点磷酸化HSFA4A，丝氨酸- 309是主要的磷酸化位点。MPK3和MPK6丝裂原活化蛋白激酶途径的激活导致热休克蛋白17.6 a基因的转录激活。与丝氨酸- 309向丙氨酸的突变强烈降低HSFA4A的磷酸化一致，它也强烈降低了热休克蛋白17.6 a的转录激活。这些数据表明，HSFA4A是MPK3/MPK6信号的底物，并调节拟南芥的应激反应。
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.