Control of mating-type switching by Sir2 and condensin

Sir2 和 condensin 控制交配型转换

• 批准号: 9894360
• 负责人: Jeffrey Scott Smith
• 金额: $ 8.5万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-13 至 2022-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9894360
• 关键词: Architecture; Binding; Binding Sites; Biological Assay; Cell Cycle; Cell Cycle Progression; Cells; Chromatin; Chromatin Interaction Analysis by Paired-End Tag Sequencing; Chromosome Structures; Chromosomes; Cis-Acting Sequence; DNA; DNA Double Strand Break; Double Strand Break Repair; Enhancers; Eukaryotic Cell; Gene Silencing; Genes; Genetic Recombination; Genetic Transcription; Genome; Heterochromatin; Interphase Cell; Kinetics; Mass Spectrum Analysis; Mating Types; Measures; Mediating; Mitotic Chromosome; Molecular; Molecular Conformation; Mothers; Nuclear; Pattern; Process; Property; Proteins; RNA; Role; Saccharomycetales; Sir2-like Deacetylases; Site; Structure; System; Testing; Time; Transcriptional Regulation; Untranslated RNA; activating transcription factor; chromosome movement; condensin; crosslink; daughter cell; ds-DNA; endonuclease; homologous recombination; preference; promoter; rapid technique; recruit; repaired; transcription factor

Project Summary. Since the first descriptions of mating-type switching in budding yeast approximately 40 years ago, characterization of this process has led to numerous key advances in understanding the mechanisms of gene silencing (heterochromatin), cell-fate determination (mating-type), and homologous recombination. For example, the highly conserved NAD+-dependent protein deacetylase, Sir2, and other “silent information regulator (SIR) proteins, were initially identified due to their roles in silencing the heterochromatic HMLα and HMRa loci, which are maintained as silenced copies of the active MATα and MATa loci, respectively. Mating-type switching occurs when a programmed dsDNA break is generated at the MAT locus by an endonuclease called HO. The break is then repaired through homologous recombination using either HMLα or HMRa as a template, with a strong preference for switching to the opposite mating type. Such “donor preference” in switching is directed by a cis-acting sequence adjacent to HMLα called the recombination enhancer (RE). Numerous chromatin factors have been implicated in mating-type switching, but mechanisms involving chromosome structural dynamics have remained elusive. In this proposal we investigate a newly discovered process of coordinating the “sensing” of an HO-induced dsDNA break at the MAT locus with requisite chromosome III structural changes. Within the RE we identified a strong binding site for Sir2, condensin, and cohibin (Lrs4/Csm1) at the promoter of a long non-coding RNA (lncRNA) gene called RDT1. This site maintains chromosome III in a switching- competent structural conformation. Sir2 normally represses RDT1 transcription in non-switching cells, but is redistributed to the HO-induced break site at MAT, which activates RDT1 transcription and triggers mating-type switching. We propose 3 specific aims that will determine not only how RDT1 lncRNA induces switching, but also investigate the roles of condensin and cohibin in the programmed structural reorganization of chromosome III. This provides a unique and well-defined system for elucidating condensin function outside of mitotic chromosome compaction, something currently missing in the field.

项目摘要。 自从大约40年前的崭露头角的首次描述交配型转换萌芽中 这个过程的表征导致了理解机制的许多关键进步 基因沉默（异染色质），细胞效果测定（交配型）和同源记录。 例如，高度保守的NAD+依赖性蛋白脱胶酶，SIR2和其他“静音” 信息调节蛋白（SIR）蛋白被原始确定，因为它们在沉默中的作用 杂色HMLα和HMRA基因座，它们被维持为活性MATα和 MATA基因座分别发生时。 垫子通过核酸内切酶，称为HO。 使用HMLα或HMRA作为模板重组 相反的交配类型。 HMLα称为重组增强子（RE）。 交配型切换，但是机制涉及染色体结构动力学已修复 难以捉摸。 HO诱导的DSDNA在MAT基因座上断裂，并在您内部进行了必要的III染色体变化 Re我们在A的启动子处鉴定 长的非编码RNA（LNCRNA）基因称为RDT1。 统一的结构固定。 将重新分布到MAT的HO诱导的断裂位点，该位点激活RDT1转录和触发器 交配型切换。 诱导切换，但还研究了冷凝蛋白和cohibin在编程结构中的作用 染色体III的重组。 在有丝分裂染色体组成之外的冷凝蛋白功能，目前在田间缺少。