Yoshima T, Yura T, Yanagi H
HSP Research Institute, Kyoto Research Park, Shimogyo-ku, Kyoto 600-8813, Japan.
Nucleic Acids Res. 1998 Jun 1;26(11):2580-5. doi: 10.1093/nar/26.11.2580.
DNA binding of heat shock factor 2 (HSF2) is induced during hemin-induced differentiation of human erythroleukemia cell line K562. To identify the transcriptional activation and the regulatory domains of HSF2, we constructed a series of deletion derivatives fused to the yeast GAL4 DNA binding domain and analyzed their transactivation activity. A minimal transactivation domain of HSF2 was localized to the C-terminus (residues 472-536), as in HSF1, although amino acid sequence similarity for these regions was rather limited and the potential transactivation ability was about 25% that of HSF1. The transactivation mediated by this region of HSF2 was found to be negatively regulated by the adjacent 18 amino acid segment (residues 428-445) under normal conditions. Furthermore, the latter segment, when fused to the GAL4 activation domain, markedly inhibited GAL4 activity. Extract containing most derivatives of HSF2 retaining this segment exhibited doublet or triplet bands in gel mobility shift assays with heat shock element-containing DNA, suggesting possible involvement of some factors interacting with that segment in the negative regulation. Another putative transactivation domain and two negative regulatory regions were also localized within the internal region.
在人红白血病细胞系K562的血红素诱导分化过程中，热休克因子2（HSF2）的DNA结合被诱导。为了鉴定HSF2的转录激活和调控结构域，我们构建了一系列与酵母GAL4 DNA结合结构域融合的缺失衍生物，并分析了它们的反式激活活性。与HSF1一样，HSF2的最小反式激活结构域定位于C末端（第472 - 536位氨基酸），尽管这些区域的氨基酸序列相似性相当有限，且潜在的反式激活能力约为HSF1的25%。发现在正常条件下，HSF2该区域介导的反式激活受到相邻的18个氨基酸片段（第428 - 445位氨基酸）的负调控。此外，当后者片段与GAL4激活结构域融合时，会显著抑制GAL4活性。含有保留该片段的HSF2大多数衍生物的提取物，在与含热休克元件的DNA进行凝胶迁移率变动分析时显示出双峰或三峰条带，这表明可能有一些与该片段相互作用的因子参与了负调控。另一个假定的反式激活结构域和两个负调控区域也定位于内部区域。
