Transcriptional activation of a heat shock gene promoter in sunflower embryos: synergism between ABI3 and heat shock factors
Transient expression analyses in sunflower embryos demonstrated that ABI3, a seed-specific transcription factor from Arabidopsis, activated chimaeric genes with the Ha hsp17.7 G4 promoter. Nucleotide substitutions at crucial positions of heat shock cis-elements established that they are required for the transcriptional activation involving ABI3. Trans-activation with Lp-HSFA1, a heat shock factor from tomato, reproduced the activation patterns of wild-type and mutant promoters observed with ABI3. In addition, ABI3 and Lp-HSFA1 syner-gistically activated the Ha hsp17.7 G4 promoter, but only when it contained the intact proximal and distal heat shock cis-elements. The activation domain of Lp-HSFA1 was necessary for promoter activation. An amino terminal deletion of ABI3 had dominant negative effects on activation by Lp-HSFA1. We failed to detect a substantial transcriptional activation by ABI3 in the absence of either functional heat shock factors or heat shock elements (HSEs). Furthermore, the wild-type, but not the mutant HSEs (from - 136 to - 49 in Ha hsp17.7 G4) were sufficient, in the context of a - 46 CaMV 35S promoter, to support activation by Lp-HSFA1, or Lp-HSFA1 and ABI3. These results demonstrate, for the first time, transcriptional activation of a heat shock protein promoter by ABI3. We also suggest that ABI3 functions as a transcriptional co-activator through heat shock factors.
| Main Authors: | , , |
|---|---|
| Other Authors: | |
| Format: | artículo biblioteca |
| Language: | English |
| Published: |
Blackwell Publishing
2002-01-05
|
| Subjects: | Dna-binding activity, Conserver B3 domaim, Seed maturation, C-MYB, Protein, Stress, Elements, Viviparous1, Expression, Tomato, |
| Online Access: | http://hdl.handle.net/10261/31948 http://dx.doi.org/10.13039/501100011011 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|