title: Generation of dominant-negative effects on the heat shock response in Arabidopsis thaliana by transgenic expression of a chimaeric HSF1 protein fusion construct.
abstract: Upon heat stress, heat shock factors (HSFs) control the expression of heat shock protein (HSP) genes by transcriptional activation. The perplexing multiplicity of HSF genes in Arabidopsis- 21 potential genes have been identified - renders it difficult to identify mutant phenotypes. In this study, we have attempted to generate a transdominant-negative mutant of HSF by transgenic expression of a protein fusion construct, EN-HSF1, consisting of the Drosophila engrailed repressor domain (EN) and the complete Arabidopsis AtHSF1. Transgenic lines were screened for impaired ability to induce high levels of low-molecular-weight heat shock proteins (sHSPs). Two lines, EH14-6 and EH16-3, which showed quantitative differences in the expression of EN-HSF1, were further analysed for induction of thermotolerance and heat-stress-dependent mRNAs of a number of different HSF target genes encoding different HSP and HSF. The mRNA levels of all genes tested were moderately downregulated in EH14-6 but strongly reduced in EH16-3 plants compared to wild-type (Wt) and HSF1-overexpressing control plants. The inhibition of the induction of heat shock response correlated with impaired basal and acquired thermotolerance of the EH16-3 line. The kinetics of HSP expression suggest that the negative effect of EN-HSF1 is stronger in the early phase of the heat shock response, and that the reduction in mRNA levels is partially compensated at the translational level.
authors.affiliation: Zentrum für Molekularbiologie der Pflanzen, Allgemeine Genetik, Universität Tübingen, 72076 Tübingen, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Wunderlich
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Werr
authors.forename: Friedrich
authors.initials: F
authors.lastname: Schöffl
mesh_terms: D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000502:physiology; D004268:DNA-Binding Proteins / Q000096:biosynthesis; D018506:Gene Expression Regulation, Plant; D005799:Genes, Dominant; D005822:Genetic Vectors; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000502:physiology; D018869:Heat-Shock Response; D010940:Plant Proteins; D030821:Plants, Genetically Modified; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C000620151:HSF1 protein, Arabidopsis; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors