Functional interaction between two transcription factors involved in the developmental regulation of a small heat stress protein gene promoter.
Hahsp17.6G1 is the promoter of a small heat stress protein (sHSP) from sunflower (Helianthus annuus) that is activated during zygotic embryogenesis, but which does not respond to heat stress. We report here the cloning of a transcription factor (TF), sunflower drought-responsive element binding factor 2 (HaDREB2), by one-hybrid interaction with functional cis-elements in Hahsp17.6G1. We have analyzed the functional interaction between HaDREB2 and a second transcription factor, sunflower heat stress factor A9 (HaHSFA9), which was previously assigned to the regulation of Hahsp17.6G1. HaDREB2 and HaHSFA9 synergistically trans-activate the Hahsp17.6G1 promoter in bombarded sunflower embryos. This synergistic interaction is heat stress factor (HSF) specific and requires the binding of both factors to the promoter. The C-terminal region of HaHSFA9 is sufficient for the HSF specificity. Our results represent an example of a functional interaction between members of the Apetala 2 (HaDREB2) and HSF (HaHSFA9) families of transcription factors. We suggest new roles in zygotic embryogenesis for specific members of the AP2 transcription factor family.
Díaz-Martín
Juan
J
Instituto de Recursos Naturales y Agrobiología, Consejo Superior de Investigaciones Científicas, Apartado 1052, 41080 Seville, Spain.
Almoguera
Concepción
C
Prieto-Dapena
Pilar
P
Espinosa
José M
JM
Jordano
Juan
J
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006368:Helianthus / Q000196:embryology / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D050436:Regulatory Elements, Transcriptional / Q000235:genetics; D014026:Nicotiana / Q000235:genetics; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000235:genetics; D020798:Two-Hybrid System Techniques
D004268:DNA-Binding Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D010940:Plant Proteins; D014157:Transcription Factors