How do Synaptonemal Complex Proteins Mediate the Coordinated Processes of Crossover Recombination and Synapsis?

项目摘要 我们提出的研究旨在了解构成同源基因的分子机制。 生殖细胞形成过程中的染色体分离。减数分裂是专门的细胞分裂周期， 有效地将每条染色体的两个同源拷贝(同源)分开以分离子核 减少染色体倍性。染色体分离错误会导致携带 染色体太多或太少。同源基因分离成功的关键是事先建立 染色体之间短暂但稳定的联系；在大多数生物体中，这些联系中的大量是 由交叉重组事件形成。如何在以下对象之间高效生成交叉关联 减数分裂过程中的每对染色体仍然知之甚少，但对大多数生物来说，很明显 这一过程涉及大规模染色体运动和局部DNA修复之间的精细协调 流程。沿长度方向组装一种保守的富含蛋白质的结构--联会复合体(SC) 同源配对染色体轴的关系调节密切的配对，并形成DNA 修复中间体成熟。长期以来，SC一直与成功的交叉重组联系在一起，并且 尽管我们最近的研究表明，SC结构本身对于在 对于发芽酵母，我们还表明SC构建块组件ZIP1具有遗传上可分离的 在促进跨界方面发挥作用。一项结构-功能研究确定了20个N末端氨基酸，它们扮演着一个 在ZIP1的S专业交叉功能和其组装SC的能力方面都发挥了关键作用。我们的数据表明 ZIP1‘S N端残基通过与前交叉蛋白相互作用来实现其交叉功能 E3相扑连接酶、Zip3。此外，在纽卡斯尔大学戴维斯实验室的合作下，我们已经开始 可能与ZIP1的S N端相连的SC的另外两个积木的结构分析 在SC组装过程中。我们建议的实验旨在支持独特的丰富培训环境 Weselyan大学的几名本科生和一名研究生；这些学生将进行 主要是分子遗传学。酵母菌的细胞学和生化方法鉴定和表征 促进同源异种间交叉重组和同源异源交叉重组协调减数分裂过程的因素 SC组件，通过与ZIP1的N端的接口。

Project Summary Our proposed research is aimed at understanding 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 chromosomes; in most organisms a large number of these links are formed by crossover recombination events. How crossover associations 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. Assembly of a conserved protein-rich structure, the synaptonemal complex (SC), along the length of homologous partner chromosome axes mediates an intimate alignment and forms the 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. A structure-function study identified twenty N terminal amino acids that play a key role in both Zip1’s specialized crossover function and in its capacity to assemble SC. Our data indicate that Zip1’s N terminal residues carry out their crossover function by interfacing with the pro-crossover protein and E3 SUMO ligase, Zip3. Moreover, in collaboration with the Davies lab at Newcastle University, we have begun a structural analysis of two additional building blocks of the SC that likely interface with Zip1’s N terminus during SC assembly. Our proposed experimets are designed to support a uniquely rich training environment for several undergraduates and one graduate student at Weselyan University; these students will undertake primarily molecular genetic. cytological and biochemical approaches in yeast to identify and characterize the factors that promote the coordinated landmark meiotic processes of interhomolog crossover recombination and SC assembly, via an interface with the N terminus of Zip1.