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Regulatory mechanisms of gene expression through the interactions of transcription factors in plants

植物中转录因子相互作用的基因表达调控机制

基本信息

批准号：
04454013
负责人：
IWABUCHI Masaki
金额：
$ 4.22万
依托单位：
KYOTO 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：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

Focusing on the transcription factors, HBP-1a and HBP-1b, that bind to the hexamer sequence in the type I element which defines the S phase-specific transcription of a wheat histone H3 gene (TH012), we investigated the structures and functions of the members of the HBP-1 transcription factor family and other transcription factors that interact with these members. Within a research term, we obtained the following results.1. The members of the HBP-1 family differ in their ability of the dimer formation and their affinity for DNA-binding. This finding suggests a possibility that the HBP-1 family members would control the gene expression by changing the partners of the members to from homo- or hetero-dimers through the bZIP domain.2. A DNA-binding protein (OBRF) was identified which specifically interacts with an octamer sequence, another cis-sequence within the type I element, by the DNA mobility shift assay of the nuclear extract from wheat cultured cells. Although OBRF was labile, its DNA-binding activity was the highest at the S phase of cell cycle and parallel with the level of the histone H3 gene expression through the cell cycle.3. A cDNA clone encoding the protein, termed HALF1, was isolated which associates with HBP-1a(17) through the protein-protein interactions by the West-western screening method. Sequence analysis of the cDNA clone revealed that an overall structure of HALF1 resembles that of the HBP-1a subfamily. The DNA-binding experiments showed that HALF1 can not bind to DNA (hexamer sequence) as a homodimer but interact with DNA as a heterodimer containing HBP-1a(17). The results suggest that HALF1 may be involved in the H3 gene regulation through the interaction with the members of the HBP-1a subfamily.

重点关注与 I 型元件中的六聚体序列结合的转录因子 HBP-1a 和 HBP-1b，该元件定义了小麦组蛋白 H3 基因 (TH012) 的 S 期特异性转录，我们研究了 HBP-1 转录因子家族成员以及与这些成员相互作用的其他转录因子的结构和功能。在一个研究期内，我们取得了以下成果： 1． HBP-1 家族成员的二聚体形成能力和 DNA 结合亲和力不同。这一发现表明HBP-1家族成员可能通过bZIP结构域将成员的伴侣改变为同源二聚体或异源二聚体来控制基因表达。2．通过对小麦培养细胞核提取物进行 DNA 迁移率变动分析，鉴定出一种 DNA 结合蛋白 (OBRF)，它与八聚体序列（I 型元件内的另一个顺式序列）特异性相互作用。尽管OBRF不稳定，但其DNA结合活性在细胞周期的S期最高，并且与细胞周期中组蛋白H3基因的表达水平平行。3．编码该蛋白质的 cDNA 克隆被分离出来，称为 HALF1，它通过 West-western 筛选方法通过蛋白质-蛋白质相互作用与 HBP-1a(17) 结合。 cDNA克隆的序列分析表明HALF1的整体结构与HBP-1a亚家族相似。 DNA 结合实验表明，HALF1 不能以同二聚体形式与 DNA（六聚体序列）结合，而是以含有 HBP-1a 的异二聚体形式与 DNA 相互作用(17)。结果表明HALF1可能通过与HBP-1a亚家族成员的相互作用参与H3基因调控。