MOLECULAR MECHANISMS OF TRANSCRIPTIONAL REPRESSION

转录抑制的分子机制

• 批准号: 6042164
• 负责人: ROBERT T SIMPSON
• 金额: $ 25.93万
• 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 2004-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6042164
• 关键词: Saccharomyces cerevisiae; chromatin; fungal genetics; gene induction /repression; genetic models; genetic promoter element; genetic recombination; genetic regulation; genetic regulatory element; genetic transcription; nucleic acid sequence; nucleic acid structure; nucleosomes; protein protein interaction; transcription factor

Transcriptional repression serves widely in gene regulation in eukaryotes. Locus control, silencing, sex chromosome dosage compensation, imprinting and other epigenetic effects involve chromatin as a means of repression. In approaching the molecular mechanism of repression in the yeast model, we have determined the nucleosomal organization of several yeast domains: the two HM loci, two a-cell specific genes, and the recombination enhancer. Each of these as a common feature, close packed dimeric nucleosomes, and a unique feature, quantized linker length of DNA between these dimers. Based on the specific repressors that nucleate the structures and co-repressors that interact with histone tails, I postulate specific architecture for each of the three types of domains we have defined. The first half of this proposal deals with testing the model structures by quantitative determination of the composition of chromatin for each unique strain, definition of the kinetics and stabilities of proposed interactions between repressors, co-repressors and chromatin, and morphological and physicochemical study of the domains assembled in vivo and in vitro. The recombination enhancer discovered by Haber and characterized structurally by our laboratory, differentially controls the recombination potential of the left arm of chromosome III in the two yeast haploid cell types. It facilitates interactions between the MATa locus and HMLalpha in mating type interconversion. In the second part of this proposal, we address the mechanisms of long range communication among these three elements by identification of proteins that interact with the recombination enhancer and study of the structures of all three elements during induced synchronous mating type switching. We will also study the silent loci to address the seeming paradox of a chromatin structure that precludes transcription yet is perfectly appropriate for recombination or transposon integration. The proposed research takes a wide range of experimental approach to two fundamental questions in gene regulation, the chromosomal organization of extensive repressed domains and long range communication between chromatin domains.

转录抑制在真核生物的基因调节中广泛使用。基因座控制，沉默，性染色体剂量补偿，印迹和其他表观遗传效应涉及染色质作为抑制作用。在接近酵母模型中抑制的分子机制时，我们确定了几种酵母菌域的核小体组织：两个HM基因座，两个A细胞特异性基因和重组增强子。这些都作为共同特征，封闭的二聚体核小体和独特的特征，量化这些二聚体之间DNA的连接器长度。 基于与组蛋白尾巴相互作用的结构和共抑制剂成核的特定阻遏物，我假设我们定义的三种域中的每一种都有特定的结构。该提案的前半部分涉及通过定量确定每个独特菌株的染色质组成，动力学的定义以及在阻遏物，共抑制剂和染色质酸层之间的拟议相互作用的稳定性以及对域中组装的域In Vivo和In Interro的域的物理化学研究的稳定性来测试模型结构。由Haber发现的重组增强剂并由我们的实验室结构表征，差异地控制了两种酵母单倍体细胞类型中染色体III左臂的重组潜力。它促进了MATA基因座和HMLALPHA之间的相互作用，在交配类型互换中。在本提案的第二部分中，我们通过鉴定与重组增强子相互作用的蛋白质以及在诱导同步配合类型切换过程中所有三个元素的结构进行研究，以解决这三个要素之间远程通信之间的机制。我们还将研究无声基因座，以解决排除转录的染色质结构的悖论，但完全适合重组或转座子整合。拟议的研究对基因调节的两个基本问题采用了广泛的实验方法，染色质结构域之间的染色体组织具有广泛的抑制域和长距离通信。