Mechanism of Meiotic Recombination

减数分裂重组机制

• 批准号: 7288927
• 负责人: MICHAEL J LICHTEN
• 金额: --
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7288927
• 关键词: Mechanism; Meiotic; Recombination

Our research examines the molecular mechanism of recombination and DNA damage repair in the yeast Saccharomyces cerevisiae. Our primary focus is on meiotic recombination, but we also study events that occur during vegetative growth. Current research involves three aspects of these complex biological processes: Initiation of meiotic recombination: Meiotic recombination is initiated by DNA double-strand breaks (DSBs); both the location and timing of break formation is tightly controlled. Our aim is to determine the proteins that form DSBs, their substrate requirements, and the factors that control their location, frequency and timing. Current research is directed at determining the composition of the protein complex that catalyzes DSB formation and at determining the chromosome structural elements that determine where DSBs do and do not form. Mechanism of meiotic recombination: We have developed techniques to isolate and characterize unstable intermediates in meiotic recombination, and have used these techniques to demonstrate that the two classes of meiotic recombination (events associated with crossing-over versus events not accompanied by crossing-over) proceed by distinct molecular mechanisms. Our current aim is to determine the repair proteins that participate in both pathways, that are unique to one or the other pathway, and that determine the choice between crossover and noncrossover recombination. Chromatin modification and double-strand break repair: We are examining changes in chromatin structure and modification that occur in response to DNA double-strand breaks, using as a model system a single DSB formed by the HO endonuclease in vegetative cells. We have shown that a large region of chromatin (> 40 kb) is modified, by phosphorylation of histone H2A, in response to this defined DSB. This phosphorylation is catalyzed by the yeast homologs of the ATM and ATR DNA damage response kinases, and is necessary for the post-replicative recruitment of cohesin to broken chrommosomes. Current research is aimed at examining similar events in meiosis.

我们的研究探讨了酿酒酵母重组和 DNA 损伤修复的分子机制。我们的主要重点是减数分裂重组，但我们也研究营养生长过程中发生的事件。目前的研究涉及这些复杂生物过程的三个方面： 减数分裂重组的启动：减数分裂重组是由DNA双链断裂（DSB）启动的；断裂形成的位置和时间都受到严格控制。我们的目标是确定形成 DSB 的蛋白质、其底物要求以及控制其位置、频率和时间的因素。目前的研究旨在确定催化 DSB 形成的蛋白质复合物的组成，以及确定决定 DSB 形成和不形成位置的染色体结构元件。 减数分裂重组机制：我们开发了分离和表征减数分裂重组中不稳定中间体的技术，并使用这些技术来证明两类减数分裂重组（与交换相关的事件与不伴随交换的事件）的进行通过不同的分子机制。我们当前的目标是确定参与这两种途径的修复蛋白，这些修复蛋白对于一种或另一种途径是独特的，并决定交叉重组和非交叉重组之间的选择。 染色质修饰和双链断裂修复：我们正在研究因 DNA 双链断裂而发生的染色质结构变化和修饰，使用由营养细胞中 HO 核酸内切酶形成的单个 DSB 作为模型系统。我们已经证明，通过组蛋白 H2A 的磷酸化，染色质的大区域 (> 40 kb) 会被修饰，以响应此定义的 DSB。这种磷酸化是由 ATM 和 ATR DNA 损伤反应激酶的酵母同源物催化的，对于复制后将粘连蛋白募集到断裂的染色体是必需的。目前的研究旨在检查减数分裂中的类似事件。