Study on signals involved in the cis-trans interactions for S phase-specific transcription in plants

本研究旨在阐明I型元件在小麦组蛋白基因发育过程中S期特异性转录调控中的作用。现将近两年的工作成果总结如下：1)稳定转化细胞中I、II、III型元素的结构比较及其功能分析：发现了与I型元素功能相同的顺式元素，由Hex和Oct基序组成。顺式元件被称为II型和III型元件，它们都包含Oct基序以及I型元件。除了Oct基序外，这三个元件还具有另一个特征基序，并且每个元件中两个基序之间的协同作用对于组蛋白启动子的S期特异性活性是必不可少的。从我们之前的结果来看，我们假设Hex基序特异性DNA结合蛋白HBP-1a和1b可能在Oct基序上招募OBRF。2) I型元件在转基因烟草植株中的功能分析：为了研究I型元件在植物发育过程中的功能，我们检测了CaMV35S最小启动子的启动子活性与I型元件在主根无活性而在侧根和茎尖有活性的启动子活性是否存在差异。这表明I型元件必须与其他顺式元件合作才能赋予H3启动子分生组织特异性活性。

The present study aimed to etucidate what is the role of the type I element involved in the S phase-specific transcription regulation of wheat histone genes during the development. The results obtained in the past two years are summarized as follows.1) Structural comparisons of the type I,II and III elements and their functional analysis in stable transformed cells : The cis-elements having the same function as the type I element, consisting of the Hex and Oct motifs, were found. The cis-elements are termed type II and III elements, and both of which contain the Oct motif as well as the type I element. These three elements were shown to have another characteristic motif in addition to the Oct motif, and the cooperative action between two motifs in each element was indispensable for S phase-specific activity of the histone promoter. From the results together with our previous ones, it has been postulated that the Hex motif-specific DNA binding proteins, HBP-1a and-1b, may function to recruit an OBRF on the Oct motif.2) Functional analysis of the type I element in transgenic tobacco plants : To investigate the function of the type I element during the development of plants, we examined whether or not there is any difference in promoter activity between the CaMV35S minimal promoter with the type I element was inactive in the main root although active in the lateral roots and shoot apex. This suggests that the type I element must cooperate with other cis-elements to confer meristem-specific activity to the H3 promoter.