Nimmo E R, Pidoux A L, Perry P E, Allshire R C
Cancer Research Campaign Project, Western General Hospital, Edinburgh, UK.
Nature. 1998 Apr 23;392(6678):825-8. doi: 10.1038/33941.
During meiotic prophase, chromosomes frequently adopt a bouquet-like arrangement, with their telomeres clustered close to the nuclear periphery. A dramatic example of this occurs in the fission yeast, Schizosaccharomyces pombe, where all telomeres aggregate adjacent to the spindle pole body (SPB). Nuclei then undergo rapid traverses of the cell, known as 'horsetail' movement, which is led by the SPB dragging telomeres and chromosomes behind. This process may initiate or facilitate chromosome pairing before recombination and meiosis. With the aim of identifying components involved in telomere structure and function, we report here the isolation of S. pombe mutants defective in the ability to impose transcriptional silencing on genes placed near telomeres. Two of these mutants, lot2-s17 and lot3-uv3, also display a dramatic lengthening of telomeric repeats. lot3-uv3 carries a mutation in Taz1, a telomere-binding protein containing a Myb-like motif similar to two human telomere-binding proteins. Meiosis is aberrant in these mutant yeast strains, and our analysis demonstrates a decreased association of telomeres with the SPB in meiotic prophase. This results in defective 'horsetail' movement, a significant reduction in recombination, low spore viability and chromosome missegregation through meiosis.
在减数分裂前期，染色体常常呈现出一种花束状排列，其端粒聚集在靠近核周边的位置。裂殖酵母（Schizosaccharomyces pombe）中就出现了一个显著的例子，在那里所有端粒都聚集在纺锤体极体（SPB）附近。然后细胞核会在细胞内快速移动，即所谓的“马尾”运动，这是由SPB拖动端粒和染色体在后面移动导致的。这个过程可能在重组和减数分裂之前启动或促进染色体配对。为了鉴定参与端粒结构和功能的成分，我们在此报告分离出了在对位于端粒附近的基因施加转录沉默能力上有缺陷的粟酒裂殖酵母突变体。其中两个突变体，lot2 - s17和lot3 - uv3，还表现出端粒重复序列的显著延长。lot3 - uv3在Taz1中携带一个突变，Taz1是一种端粒结合蛋白，含有一个类似于两个人类端粒结合蛋白的Myb样基序。在这些突变酵母菌株中减数分裂异常，我们的分析表明在减数分裂前期端粒与SPB的结合减少。这导致“马尾”运动缺陷、重组显著减少、孢子活力低以及减数分裂过程中的染色体错配。
