The Nucleoporin Nup2 Contains a Meiotic-Autonomous Region that Promotes the Dynamic Chromosome Events of Meiosis
The Nucleoporin Nup2 Contains a Meiotic-Autonomous Region that Promotes the Dynamic Chromosome Events of Meiosis
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DOI：
10.1534/genetics.116.194555
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发表时间：
2017-07-01
期刊：
影响因子：
3.3
通讯作者：
Burgess, Sean M.
中科院分区：
文献类型：
--
作者：
Chu, Daniel B.;Gromova, Tatiana;Burgess, Sean M.
减数分裂是从二倍体亲本细胞产生单倍体配子所需的专门细胞程序。同源染色体配对，突触，并在一个动态的环境中重组，容纳总染色体重组和显着的染色体运动，这是正常的染色体分离的关键。在酿酒酵母中，Ndj 1是一种减数分裂端粒相关蛋白，用于将端粒物理连接到包埋在核膜中的蛋白质上。在这项研究中，我们确定了额外的蛋白质，作用于减数分裂细胞提取物的核周边，包括Nup 2，一个非必需的核孔蛋白与一个已知的作用拴系间质染色体位点的核孔复合物。我们发现，NUP 2的删除影响减数分裂的进程和孢子的活力，并给出了重组中间体和产品的水平增加。我们确定了一个以前未知的125个氨基酸区域的Nup 2是必要的和足够的减数分裂功能，从而表现为一个减数分裂自治区（MAR）。Nup 2-MAR在分散的减数分裂染色体上形成不同的焦点，其中一个子集与Ndj 1焦点重叠。Nup 2-MAR定位到减数分裂染色体不需要Ndj 1，Ndj 1定位也不需要Nup 2，这表明这些蛋白质在不同的途径中起作用，并且它们的相互作用是弱的或间接的。相反，一些严重的合成表型与nup 2 Delta ndj 1 Delta双突变体相关，包括重组联合分子的延迟周转，以及在不阻止减数分裂程序的情况下不能进行核分裂。这些数据表明，Nup 2和Ndj 1支持部分重叠的功能，促进两个不同水平的减数分裂染色体组织必须承受的真核生命周期的动态阶段。
Meiosis is a specialized cellular program required to create haploid gametes from diploid parent cells. Homologous chromosomes pair, synapse, and recombine in a dynamic environment that accommodates gross chromosome reorganization and significant chromosome motion, which are critical for normal chromosome segregation. In Saccharomyces cerevisiae, Ndj1 is a meiotic telomere-associated protein required for physically attaching telomeres to proteins embedded in the nuclear envelope. In this study, we identified additional proteins that act at the nuclear periphery from meiotic cell extracts, including Nup2, a nonessential nucleoporin with a known role in tethering interstitial chromosomal loci to the nuclear pore complex. We found that deleting NUP2 affects meiotic progression and spore viability, and gives increased levels of recombination intermediates and products. We identified a previously uncharacterized 125 aa region of Nup2 that is necessary and sufficient for its meiotic function, thus behaving as a meiotic autonomous region (MAR). Nup2-MAR forms distinct foci on spread meiotic chromosomes, with a subset overlapping with Ndj1 foci. Localization of Nup2-MAR to meiotic chromosomes does not require Ndj1, nor does Ndj1 localization require Nup2, suggesting these proteins function in different pathways, and their interaction is weak or indirect. Instead, several severe synthetic phenotypes are associated with the nup2 Delta ndj1 Delta double mutant, including delayed turnover of recombination joint molecules, and a failure to undergo nuclear divisions without also arresting the meiotic program. These data suggest Nup2 and Ndj1 support partially overlapping functions that promote two different levels of meiotic chromosome organization necessary to withstand a dynamic stage of the eukaryotic life cycle.