Raschke E, Baumann G, Schöffl F
Universität Bielefeld, Fakultät für Biologie (Genetik), F.R.G.
J Mol Biol. 1988 Feb 20;199(4):549-57. doi: 10.1016/0022-2836(88)90300-2.
In soybean, the small heat shock proteins of 15 to 18 kDa are encoded in the nucleus by at least two different multigene families, designated class I and class VI. Genomic DNA sequences of two new heat shock genes and flanking regions were determined: Gmhsp18.5-C, a class I gene, and Gmhsp17.9-D, the first known class VI gene. Comparison of both genes revealed a moderate homology (approx. 38%) mainly within the 3' ends of their coding regions. Hydropathic characterizations and secondary-structure predictions of the deduced amino acid sequences revealed two conserved domains within the C-terminal halves of the polypeptides that are also present in related proteins of other organisms. The transcription of both genes is heat shock dependent and the mRNA start sites, as determined by S1 nuclease mapping, are located downstream from typical TATA box sequences and multiple heat shock promoter elements such as 5' CT-GAA--TTC-AG. The putative promoter regions of the genes are preceded by long tracts of repetitive sequences with a high A + T content of 79 to 89%, which are bordered by runs of "simple sequences" such as (A) 12/13, (T)10 and (TA)10. Similar characteristic features are present in the promoter and 5'-flanking regions of other soybean heat shock genes. The possible function of these distinct sequences is discussed.
在大豆中，15至18 kDa的小热激蛋白由细胞核中至少两个不同的多基因家族编码，分别命名为I类和VI类。测定了两个新的热激基因及其侧翼区域的基因组DNA序列：I类基因Gmhsp18.5-C和首个已知的VI类基因Gmhsp17.9-D。对这两个基因的比较显示，它们在编码区的3'端主要具有中等程度的同源性（约38%）。对推导的氨基酸序列进行亲水性特征分析和二级结构预测，发现在多肽的C端半部存在两个保守结构域，其他生物体的相关蛋白中也有这些结构域。这两个基因的转录都依赖于热激，通过S1核酸酶作图确定，mRNA起始位点位于典型的TATA盒序列和多个热激启动子元件（如5' CT-GAA--TTC-AG）的下游。这些基因的推定启动子区域之前有长段的重复序列，A + T含量高达79%至89%，其边界是由（A）12/13、（T）10和（TA）10等“简单序列”组成的序列段。其他大豆热激基因的启动子和5'侧翼区域也有类似的特征。文中讨论了这些独特序列可能的功能。
