The heat stress transcription factor HsfA2 serves as a regulatory amplifier of a subset of genes in the heat stress response in Arabidopsis
The heat stress transcription factor HsfA2 serves as a regulatory amplifier of a subset of genes in the heat stress response in Arabidopsis
复制标题
DOI：
10.1007/s11103-005-5750-x
复制
发表时间：
2006-03-01
影响因子：
5.1
通讯作者：
von Koskull-Döring, P
中科院分区：
文献类型：
--
作者：
Schramm, F;Ganguli, A;von Koskull-Döring, P
在由 21 个热应激转录因子 (Hsfs) 组成的拟南芥家族中，HsfA2 是热应激 (hs) 条件下表达最强的成员。无论何种组织，HsfA2 在热应激下都会积聚，与其他热应激蛋白 (Hsp) 类似。分析了具有完全 HsfA2 敲除的 SALK T-DNA 插入系在热应激条件下转录组的变化。除了几个 sHsp、Hsp70 和 Hsp100 家族的个体成员以及许多功能尚不清楚的基因转录本之外，抗坏血酸过氧化物酶 2 (APX2) 被确定为受影响最严重的转录本。为了进行功能验证，使用叶肉原生质体中的瞬时报告基因测定分析了含有所选靶基因的 1 kb 上游启动子序列的 GUS 报告基因构建体上 HsfA2 的转录激活潜力。通过缺失分析，对受影响最强的靶基因 APX2 的启动子区域进行了详细的功能定位，以验证潜在的 HsfA2 结合位点。通过电泳迁移率变动分析，我们确定了选定靶基因启动子中热应激元件 (HSE) 的 TATA-Box 近端簇作为潜在的 HsfA2 结合位点。本文提出的结果表明，拟南芥中 HsfA2 的表达严格依赖于热应激，并且该转录因子代表拟南芥中应激反应基因子集的调节因子。
Within the Arabidopsis family of 21 heat stress transcription factors (Hsfs) HsfA2 is the strongest expressed member under heat stress (hs) conditions. Irrespective of the tissue, HsfA2 accumulates under heat stress similarly to other heat stress proteins (Hsps). A SALK T-DNA insertion line with a complete HsfA2-knockout was analyzed with respect to the changes in the transcriptome under heat stress conditions. Ascorbate peroxidase 2 (APX2) was identified as the most affected transcript in addition to several sHsps, individual members of the Hsp70 and Hsp100 family, as well as many transcripts of genes with yet unknown functions. For functional validation, the transcription activation potential of HsfA2 on GUS reporter constructs containing 1 kb upstream promoter sequences of selected target genes were analyzed using transient reporter assays in mesophyll protoplasts. By deletion analysis the promoter region of the strongest affected target gene APX2 was functionally mapped in detail to verify potential HsfA2 binding sites. By electrophoretic mobility shift assays we identified TATA-Box proximal clusters of heat stress elements (HSE) in the promoters of selected target genes as potential HsfA2 binding sites. The results presented here demonstrate that the expression of HsfA2 in Arabidopsis is strictly heat stress-dependent and this transcription factor represents a regulator of a subset of stress response genes in Arabidopsis.