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Molecular Mechnisms of Meristematic Tissue-Specific Expression of Plnat Histone Genes Introduced by a Ti-Plasmid Vector, Especially concerning Cis-Acting Control Elements for the Initiation and Termination of

由 Ti 质粒载体引入的 Plnat 组蛋白基因分生组织特异性表达的分子机制，特别是关于启动和终止的顺式作用控制元件

基本信息

批准号：
61480007
负责人：
IWABUCHI Masaki
金额：
$ 3.84万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

项目摘要

During the last two years, in order to study the molecular mechanisms of the transcriptional regulation of the genes which are specifically experssed at the S phase during cell cycle, we have examined the cis- and trans-acting Control elements of the histone genes using the cloned wheat histone H3 and H4 genes. To examine the transcriptional activity of the histone gene, the Ti-plasmid mediated gene transfer system was used; the wheat histone genes were introduced into sunflower hypocotyl cells via Ti-plasmid and the transcripts of the wheat genes in transformed cells were measured by the S1 assay.The analysis of the transcriptional activities of the 5' deletion mutants of the H3 and H4 genes revealed that some cis-elements promoting a high efficiency of the transcription are located between the positions -668 and 191 and that the hexameric sequence just upstream from the octameric sequence which exists in all plant histone genes examined so far seemd to have some connection with the transcriptional regulation. On the other hand, the octameric sequence was not shown to be a motif to regulate the transcription of the histone genes.Several experiments using the gel retardation assay, methylation interference assay and DNase I footprint method have demonstrated that there exist nuclear protein(s) specifically binding to the hexameric sequence in wheat cells. The nuclear protein Which was tentatively termed HBP-1 are more abundantly contained in germinating than dormant germs. Furthermore, in wheat seedling in which the cell cycle was partially synchronized by aphidicoline treatment, HBP-1 was persent in the highest concentration in the nuclear extract from an S phase-abundant cell population. These data have suggested that the hexameric sequence and HBP-1 are cis- and trans-acting control elements, respectively, involved in cell cycle-dependent transcription of the wheat histone genes.

在过去的两年中，为了研究特异表达于细胞周期S期的基因的转录调控的分子机制，我们利用克隆的小麦组蛋白H3和H4基因检测了组蛋白基因的顺式和反式调控元件。为了检测组蛋白基因的转录活性，使用Ti质粒介导的基因转移系统;利用Ti质粒将小麦组蛋白基因导入向日葵下胚轴细胞，用S1法测定了小麦组蛋白基因在转化细胞中的转录活性，对H3和H4基因5'端缺失突变体的转录活性分析表明，部分顺式-促进高转录效率的元件位于-668和191位之间，并且存在于迄今为止所研究的所有植物组蛋白基因中的八聚体序列上游的六聚体序列被认为与转录调节有某种联系。利用凝胶阻滞试验、甲基化干扰试验和DNA酶I足迹法等方法，证实了小麦细胞中存在与六聚体序列特异性结合的核蛋白。核蛋白HBP-1在萌发期比休眠期含量丰富。此外，在细胞周期部分同步化的小麦幼苗中，HBP-1在来自S期丰富的细胞群的核提取物中以最高浓度存在。这些数据表明，六聚体序列和HBP-1的顺式和反式作用的控制元件，分别参与细胞周期依赖的转录的小麦组蛋白基因。