Molecular Organization of Yeast Chromosome I - Control of Meiotic Pairing and Recombination

酵母 I 号染色体的分子组织 - 减数分裂配对和重组的控制

• 批准号: 0136278
• 负责人: David Kaback
• 金额: $ 47万
• 依托单位: Rutgers, The State University of New Jersey-RBHS-New Jersey Med
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-06-01 至 2005-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0136278&HistoricalAwards=false
• 关键词: Molecular; Organization; Yeast; Chromosome; Control; Molecular; Organization; Yeast; Chromosome; Control

SUMMARY Reciprocal recombination (crossing over) between homologous chromosomes (homologues) appears to be required for proper meiosis I segregation. The mechanisms that control recombination so that each pair of homologues undergoes crossing over are not known. In Saccharomyces cerevisiae and humans, small chromosomes have higher meiotic reciprocal recombination rates (cM/kb) than large chromosomes and in S. cerevisiae rates of reciprocal recombination have been shown to respond directly to chromosome size. The increased rates of recombination on small chromosomes appear to ensure crossing over and have been proposed to be due to crossover interference. Interference is defined by the apparent inhibition of additional meiotic reciprocal recombination events observed near the site of a crossover. The molecular mechanism of interference and how it might respond to chromosome size are not known. It was recently suggested that the density of meiotic recombination-inducing double-strand break (DSB) sites is greater on small chromosomes compared to large chromosomes suggesting chromosome size dependent control of recombination and perhaps interference might act by controlling DSB formation. To test this idea, we propose to analyze DSB formation on different size chromosome I constructs that were constructed in our laboratory. It has also been suggested that the meiotic synaptonemal complex (SC) is involved in mediating interference. Accordingly, a better understanding of the mechanism of interference might be gained by investigating the S. cerevisiae SC. Using a functional, fluorescent ZIP1-GFP fusion protein constructed in our laboratory, we have shown that SCs undergo dynamic changes in their distribution in early and late pachytene. We now propose to examine the dynamics of SC movements using ZIP1-GFP in mutant yeast in order to determine the genes required to produce this reorganization. We also propose to address the relationship of this reorganization to crossover interference. The structure and dynamics of the fluorescent SC will be examined using optical sections and fluorescent cinema-microscopy and will be enhanced by the construction of additional ZIP1-fluorocent protein fusions. These studies should provide new insight into the molecular mechanisms controlling recombination and chromosome synapsis, processes that lead to proper meiotic chromosome segregation.

同源染色体（同源物）之间的摘要相互重组（交叉）似乎是适当的减数分裂I分离所必需的。 控制重组的机制以使每对同源物都经过交叉，尚不清楚。 在酿酒酵母和人类中，小染色体的减数分裂相互重组率（CM/kb）高于大型染色体，而在酿酒酵母中，互惠重组的速率已被证明可以直接响应染色体大小。 小染色体上的重组率的提高似乎确保了越过，并被提议是由于交叉干扰引起的。干扰是通过明显抑制了在交叉部位附近观察到的其他减数分裂相互重组事件的明显抑制。尚不清楚干扰分子机制及其对染色体大小的反应。最近有人提出，与大型染色体相比，小染色体的减数分裂重组诱导双链断裂（DSB）位点更大，表明染色体大小依赖于重组的染色体依赖性控制，并且可能通过控制DSB的形成来起作用。 为了测试这一想法，我们建议分析我们实验室中构建的不同尺寸染色体I构造的DSB形成。 还有人提出减数分裂的突触复合物（SC）参与介导干扰。因此，可以通过研究酿酒酵母SC来更好地理解干扰机理。 使用实验室中构建的功能性的荧光Zip1-GFP融合蛋白，我们表明SC在早期和晚期pachytene中的分布发生动态变化。 现在，我们建议在突变酵母中使用Zip1-GFP检查SC运动的动力学，以确定产生这种重组所需的基因。 我们还建议解决这种重组与跨界干扰的关系。 荧光SC的结构和动力学将使用光学切片和荧光电影微观镜检查进行检查，并通过构建其他Zip1-氟化蛋白融合来增强。 这些研究应提供有关控制重组和染色体突触的分子机制的新见解，这些过程导致适当的减数分裂染色体分离。