How Do Synaptonemal Complex Proteins Promote Crossover Recombination and Synapsis?

项目摘要 我们提出的研究旨在破译同源染色体的分子机制 生殖细胞形成过程中的分离。减数分裂是一个特殊的细胞分裂周期， 每个染色体的两个同源拷贝（同源物）分离子细胞核，有效地减少 染色体倍性染色体分离的错误导致非整倍体生殖细胞也携带 许多或两个少数染色体。同系物分离成功的关键是事先建立 复制染色体之间的短暂但稳定的联系;对于大多数生物体来说，这些联系是在 通过同源物间的交叉重组事件，结合完整的姐妹凝聚力。 在减数分裂过程中，每对染色体之间如何有效地产生交叉事件仍然存在 我们对此知之甚少，但对大多数生物来说，这一过程显然涉及到一种微妙的协调， 大规模染色体移动和局部DNA修复过程之间的联系。一种保守的多蛋白 联会复合体（SC）是一种重要的结构，它介导同源配偶体之间的紧密排列， 染色体轴，并形成DNA修复中间体成熟的物理环境。SC长期以来 与成功的交叉重组有关，尽管我们最近的研究表明， SC结构本身是为了在芽殖酵母中进行交换，我们还表明SC的构建 阻断组分Zip 1在促进杂交中具有遗传上可分离的功能。我们的结构-功能 分析揭示了Zip 1的N末端内的相邻结构域，其独立地起促进交换的作用 重组和SC组装，可能通过分别与亲交换E3 SUMO 连接酶、Zip 3和SC中心元件蛋白复合物Ecm 11-Gmc 2。 我们最近的数据显示，i）Zip 1的N端有一个潜在的基于磷酸化的开关， 它的交换活性，ii）鉴定了Zip 3蛋白内的几个区域，其前重组所需的 和/或前SC组装活动，iii）缩小Ecm 11和Gmc 2之间的最小相互作用界面， 和iv）证明了亲交换蛋白（以及可能的SC中央蛋白）之间的邻近标记相互作用。 元件蛋白），其由Zip 1的N末端稳定。我们提出的实验旨在 支持一个独特的丰富的培训环境，为几个本科生，一个新的“第五年”硕士生， 一名博士生，建立在我们最近的实验数据，旨在深化我们的结构和功能 理解协调重组和SC组装的分子机制。啤酒。

Project Summary Our proposed research aims to decipher the molecular mechanisms that underlie homologous chromosome segregation during reproductive cell formation. Meiosis is the specialized cell division cycle that partitions the two homologous copies of every chromosome (homologs) to separate daughter nuclei, effectively reducing chromosome ploidy. Errors in chromosome segregation lead to aneuploid reproductive cells that carry too many or two few chromosomes. Key to the success of homolog segregation is the prior establishment of transient but stable associations between replicated chromosomes; for most organisms these links are formed by interhomolog crossover recombination events, in conjunction with intact sister cohesion. How crossover events are efficiently generated between every chromosome pair during meiosis remains poorly understood, but for most organisms it is clear that the process involves an exquisite coordination between large-scale chromosome movements and local DNA repair processes. A conserved multi-protein structure, the synaptonemal complex (SC), mediates an intimate alignment between homologous partner chromosome axes and forms the physical context in which DNA repair intermediates mature. SC has long been associated with successful crossover recombination, and although our recent research demonstrated that the SC structure per se is dispensable for crossing over in budding yeast, we also showed that the SC building block component, Zip1, has a genetically separable function in promoting crossovers. Our structure-function analysis revealed adjacent domains within Zip1’s N terminus that function independently to promote crossover recombination and SC assembly, potentially through separately interfacing with the pro-crossover E3 SUMO ligase, Zip3, and the SC central element protein complex Ecm11-Gmc2. Our recent data has i) revealed a potential phosphorylation-based switch in Zip1’s N terminus that controls its crossover activity, ii) identified several regions within the Zip3 protein required for its pro-recombination and/or pro-SC assembly activities, iii) narrowed the minimal interaction interface between Ecm11 and Gmc2, and iv) demonstrated proximity labeling interactions between pro-crossover proteins (and possibly SC central element proteins) that are stabilized by Zip1’s N terminus. Our proposed experiments, which are designed to support a uniquely rich training environment for several undergraduates, a new “5th year” Masters student, and one doctoral student, build upon our recent experimental data and aim to deepen our structural and functional understanding of the molecular mechanisms that coordinate recombination and SC assembly in S. cerevisiae.