Crossing over during Caenorhabditis elegans meiosis requires a conserved MutS-based pathway that is partially dispensable in budding yeast.
Crossing over during Caenorhabditis elegans meiosis requires a conserved MutS-based pathway that is partially dispensable in budding yeast.
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发表时间：
1999-11
期刊：
影响因子：
3.3
通讯作者：
J. Zalevsky;A. MacQueen;J. B. Duffy;K. Kemphues;A. Villeneuve
中科院分区：
文献类型：
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作者：
J. Zalevsky;A. MacQueen;J. B. Duffy;K. Kemphues;A. Villeneuve
秀丽线虫减数分裂过程中同源染色体间交叉的形成需要HIM-14基因。HIM-14功能的丧失严重减少了交叉，导致同源基因之间缺乏交叉，从而导致错误分离。细胞学分析表明，HIM-14粗线期细胞核中的同源物成对排列，温度漂移实验表明HIM-14在粗线期发挥作用，表明HIM-14不需要建立配对或突触，可能在交叉形成中起更直接的作用。HIM-14编码DNA错配修复(MMR)蛋白MutS家族中一个生殖系特异的成员。HIM-14在MMR中没有明显的作用，但与它的酿酒酵母同源基因MSH4一样，在减数分裂过程中具有促进交叉的特殊作用。尽管这种保守，蠕虫和酵母对这条途径的依赖有很大的不同：尽管蠕虫使用这条途径来产生大多数(如果不是全部)交叉，但当没有这条途径时，酵母仍然形成正常数量的30-50%的交叉。这种差异依赖可能反映了具有交叉能力的重组中间体的不同稳定性，或者，酵母中存在两种不同的交叉形成途径，在线虫减数分裂过程中只有一种途径占主导地位。我们讨论了一个模型，在该模型中，HIM-14通过干扰Holliday连接分支的迁移来促进交叉。
Formation of crossovers between homologous chromosomes during Caenorhabditis elegans meiosis requires the him-14 gene. Loss of him-14 function severely reduces crossing over, resulting in lack of chiasmata between homologs and consequent missegregation. Cytological analysis showing that homologs are paired and aligned in him-14 pachytene nuclei, together with temperature-shift experiments showing that him-14 functions during the pachytene stage, indicate that him-14 is not needed to establish pairing or synapsis and likely has a more direct role in crossover formation. him-14 encodes a germline-specific member of the MutS family of DNA mismatch repair (MMR) proteins. him-14 has no apparent role in MMR, but like its Saccharomyces cerevisiae ortholog MSH4, has a specialized role in promoting crossing over during meiosis. Despite this conservation, worms and yeast differ significantly in their reliance on this pathway: whereas worms use this pathway to generate most, if not all, crossovers, yeast still form 30-50% of their normal number of crossovers when this pathway is absent. This differential reliance may reflect differential stability of crossover-competent recombination intermediates, or alternatively, the presence of two different pathways for crossover formation in yeast, only one of which predominates during nematode meiosis. We discuss a model in which HIM-14 promotes crossing over by interfering with Holliday junction branch migration.