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同源的分子机制， 生殖细胞形成过程中的染色体分离。减数分裂是一个特殊的细胞分裂周期， 将每条染色体的两个同源拷贝（同源物）有效地分割成独立的子核， 降低染色体倍性。染色体分离错误导致非整倍体生殖细胞携带 染色体过多或过少。同系物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， 由交叉重组事件形成。交叉关联如何在 减数分裂期间的每一对染色体仍然知之甚少，但对大多数生物来说， 这一过程涉及大规模染色体运动和局部DNA修复之间的微妙协调 流程.一个保守的富含蛋白质的结构，联会复合体（SC），沿沿着长度组装 同源配偶体染色体轴介导了一个紧密的对齐，并形成了DNA 修复中间体成熟。SC长期以来与成功的交换重组有关， 虽然我们最近的研究表明，SC结构本身是不适合交叉， 芽殖酵母，我们还表明，SC积木组件，Zip 1，具有遗传分离， 在促进交叉方面的作用。一项结构-功能研究确定了20个N末端氨基酸， 在Zip 1的专业交叉功能和组装SC的能力中起着关键作用。我们的数据表明， Zip 1的N末端残基通过与亲交换蛋白介接来执行其交换功能， E3 SUMO连接酶，Zip 3。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 对可能与Zip 1的N末端连接的SC的另外两个构建块的结构分析 在SC组装期间。我们建议的实验旨在支持一个独特的丰富的培训环境， 几名本科生和一名研究生在卫斯理安大学;这些学生将承担 主要是分子遗传学。酵母细胞学和生物化学方法来鉴定和表征 促进同源物间交换重组的协调标志性减数分裂过程的因素， SC组装，通过与Zip 1的N末端的接口。

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.