title: Arabidopsis HsfA1 transcription factors function as the main positive regulators in heat shock-responsive gene expression.
abstract: Arabidopsis DREB2A is a key transcription factor of heat- and drought-responsive gene expression, and DREB2A expression is induced by these stresses. We analyzed the DREB2A promoter and found a heat shock element that functions as a cis-acting element in the heat shock (HS)-responsive expression of DREB2A. Among the 21 Arabidopsis heat shock factors, we chose 4 HsfA1-type proteins as candidate transcriptional activators (HsfA1a, HsfA1b, HsfA1d, and HsfA1e) based on transactivation activity and expression patterns. We generated multiple mutants and found that the HS-responsive expression of DREB2A disappeared in hsfa1a/b/d triple and hsfa1a/b/d/e quadruple mutants. Moreover, HS-responsive gene expression, including that of molecular chaperones and transcription factors, was globally and drastically impaired in the hsfa1a/b/d triple mutant, which exhibited greatly reduced tolerance to HS stress. HsfA1 protein accumulation in the nucleus was negatively regulated by their interactions with HSP90, and other factors potentially strongly activate the HsfA1 proteins under HS stress. The hsfa1a/b/d/e quadruple mutant showed severe growth retardation, and many genes were downregulated in this mutant even under non-stress conditions. Our study indicates that HsfA1a, HsfA1b, and HsfA1d function as main positive regulators in HS-responsive gene expression and four HsfA1-type proteins are important in gene expression for normal plant growth.
authors.affiliation: Laboratory of Plant Molecular Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, 113-8657, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Yoshida
authors.forename: Naohiko
authors.initials: N
authors.lastname: Ohama
authors.forename: Jun
authors.initials: J
authors.lastname: Nakajima
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kidokoro
authors.forename: Junya
authors.initials: J
authors.lastname: Mizoi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Nakashima
authors.forename: Kyonoshin
authors.initials: K
authors.lastname: Maruyama
authors.forename: Jong-Myong
authors.initials: JM
authors.lastname: Kim
authors.forename: Motoaki
authors.initials: M
authors.lastname: Seki
authors.forename: Daisuke
authors.initials: D
authors.lastname: Todaka
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Osakabe
authors.forename: Yoh
authors.initials: Y
authors.lastname: Sakuma
authors.forename: Friedrich
authors.initials: F
authors.lastname: Schöffl
authors.forename: Kazuo
authors.initials: K
authors.lastname: Shinozaki
authors.forename: Kazuko
authors.initials: K
authors.lastname: Yamaguchi-Shinozaki
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000502:physiology; D018869:Heat-Shock Response / Q000235:genetics*; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics* / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology; D015533:Transcriptional Activation
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; C000620133:HsfA1e protein, Arabidopsis; D010940:Plant Proteins; D014157:Transcription Factors