MOLECULAR MECHANISMS OF TRANSCRIPTIONAL REPRESSION

转录抑制的分子机制

• 批准号: 2332001
• 负责人: ROBERT T SIMPSON
• 金额: $ 23.32万
• 依托单位: PENNSYLVANIA STATE UNIVERSITY, THE
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-02-09 至 2000-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2332001
• 关键词: DNA binding protein; Saccharomyces cerevisiae; centromere; chromatin; chromosomes; fungal genetics; gel mobility shift assay; gene induction /repression; genetic promoter element; genetic regulation; genetic terminator element; nucleic acid sequence; nucleic acid structure; nucleosomes; stoichiometry; telomere; transcription factor

DESCRIPTION: X-chromosome inactivation; epigenetic inheritance; position effect variegation; locus control as well as silencing at telomeres, repressed mating type loci, and centromeres are all transcriptionally regulated features of the eukaryotic genome for which chromatin structure has been suggested as a possible controlling element. The exact nature of the postulated repressive chromatin domain has not been determined for any of these cases. To explore the role of chromatin in DNA function, the investigator has focused on genes regulated by the mating type locus in a tractable, simple eukaryote, S. cerevisiae. He has shown that a repressive chromatin structure is organized by the alpha2 repressor on alpha-cell specific genes in alpha-cells. There is an absolute concordance of the presence of this organized chromatin structure with complete repression of genes under control of alpha-cell specific promoters in yeast strains bearing mutant histones or mutations in other proteins (Ssn6p and Tuplp) known to be necessary for repression of these genes. A motif of close packed dimeric nucleosomes separated by 43 bp linkers spans the entire repressed STE6 gene. This nucleosome arrangement is considered as a paradigm for organization of repressed chromatin domains. The proposed research will ascertain whether this structure also occurs for another gene controlled by the alpha2 repressor, BARI, other genes which require Ssn6p and Tuplp for repression, and model systems targeting a repressor of Tuplp to a foreign binding site. Ssn6p and Tuplp have domains which suggest their involvement in protein-protein interactions as well as interactions with nuclear matrix structures. Using improvements to the minichromosome system pioneered in the investigator's laboratory for study of chromatin composition and structure, he will isolate minichromosomes containing the STE6 gene and address directly the interaction of Ssn60 and Tuplp with the repressed gene. Biochemical studies of the interactions of these proteins with each other and chromosomal structural proteins will define the composition and structure of the repressed chromatin domain. Finally, the investigator will examine whether silenced domains such as telomeres, centromeres and the silent mating type loci also have the organized chromatin structure of close packed dimers interspersed by long linkers. To address this question, the lab will take advantage of the complete sequence of yeast chromosome III and will map chromatin structure of about 30 kb of this chromosome. While focusing on specific genomic loci in yeast, these studies are relevant to the organization of constitutively repressed genetic loci in other domains, as well as conditionally repressed genes in both yeast and larger eukaryotic cells.

描述：X染色体灭活；表观遗传遗传；位置 效果变化；基因座控制以及在端粒处沉默， 压抑的交配类型基因座和centromeres都是转录的 真核基因组的调节特征，其染色质 已经建议结构作为可能的控制元素。 这 假定的抑制性染色质结构域的确切性质尚未 确定这些情况中的任何一个。 探索染色质在 DNA功能，研究者的重点是由 酿酒酵母的可缝合，简单的真核生物中的交配类型基因座。 他 已经表明，抑制性染色质结构是由 α2在α-细胞中α-细胞特异性基因上的α2抑制剂。 有 该有组织染色质的存在的绝对一致性 结构完全抑制了α细胞控制的基因 带有突变组蛋白或突变的酵母菌菌株中的特定启动子 在其他已知是抑制必不可少的蛋白质（SSN6P和TUPLP）中 这些基因。 近距离二聚体核小体的基序分离 由43个BP接头跨越了整个被压抑的Ste6基因。 这个核小体 安排被认为是组织被压抑的范式 染色质结构域。 拟议的研究将确定是否 另一个由alpha2控制的基因也会发生结构 阻遏物，Bari，其他需要SSN6P和Tuplp的基因 镇压和模型系统将Tuplp的阻遏物瞄准外国 绑定位点。 SSN6P和TUPLP的域暗示他们 参与蛋白质 - 蛋白质相互作用以及与 核基质结构。 利用对微小物体体的改进 在研究者的实验室中率先研究染色质的系统 组成和结构，他将隔离包含含有 Ste6基因并直接解决SSN60和Tuplp与 被压抑的基因。 这些相互作用的生化研究 蛋白质彼此，染色体结构蛋白将定义 抑制染色质结构域的组成和结构。 最后，研究人员将检查是否沉默的域（例如 端粒，中心粒和沉默的交配类型基因座也有 封闭的封闭二聚体的有组织的染色质结构 长链接。 为了解决这个问题，实验室将利用 酵母染色体III的完整序列，将绘制染色质 该染色体的大约30 kb的结构。 同时专注于特定 酵母中的基因组基因座，这些研究与组织有关 组成型抑制其他领域的遗传基因座以及 在酵母和较大的真核细胞中有条件抑制基因。