Inter-homolog crossing-over and synapsis in Arabidopsis meiosis are dependent on the chromosome axis protein AtASY3.
Inter-homolog crossing-over and synapsis in Arabidopsis meiosis are dependent on the chromosome axis protein AtASY3.
复制标题
拟南芥减数分裂中的血间交叉和突触取决于染色体轴蛋白ATASY3。
DOI：
10.1371/journal.pgen.1002507
复制
发表时间：
2012-02
期刊：
影响因子：
4.5
通讯作者：
Franklin FC
中科院分区：
文献类型：
--
作者：
Ferdous M;Higgins JD;Osman K;Lambing C;Roitinger E;Mechtler K;Armstrong SJ;Perry R;Pradillo M;Cuñado N;Franklin FC
在这项研究中，我们分析了AtASY 3，一个卷曲螺旋结构域蛋白，是所需的正常减数分裂在拟南芥。对Atasy 3 -1突变体的分析表明，蛋白质的丢失损害了染色体轴的形成，并导致减数分裂交换（CO）的数量减少。尽管Atasy 3 -1中DNA双链断裂（DSB）的频率出现适度降低，但主要的重组缺陷是CO形成的减少。在野生型性母细胞中的免疫定位研究表明，HORMA蛋白AtASY 1，这是相关的芽殖酵母中的Hop 1，形成超丰富的结构域沿着染色体，空间上与DSB和早期重组途径蛋白。AtASY 3的缺失破坏了AtASY 1的轴向组织。此外，我们表明，AtASY 3和AtASY 1同源物BoASY 3和BoASY 1，从密切相关的物种甘蓝，共免疫沉淀从性母细胞提取物和AtASY 3相互作用AtASY 1通过其预测的卷曲螺旋结构域中的残基。我们的研究结果表明，AtASY 3是Red 1的功能同源物。由于在芽殖酵母中的研究表明，Red 1和Hop 1在建立偏向于同源重组（IHR）中起着关键作用，我们提出AtASY 3和AtASY 1可能在拟南芥中具有类似的作用。AtASY 3的缺失也破坏联会复合体（SC）的形成。在Atasy 3 -1中，横丝蛋白AtZYP 1形成小的斑块，而不是连续的SC。在Atasy 3 -1中保留的少数AtMLH 1病灶与AtZYP 1斑块相关。这足以防止在AtZYP 1不存在的情况下观察到的异位重组，从而强调除了其结构作用外，该蛋白质对CO形成也很重要。同源重组（HR）在减数分裂前期I导致同源染色体（同源物）之间形成物理连接，称为交叉。交叉对于第一次减数分裂时同源物的准确分离是必不可少的。HR是由DNA双链断裂（DSB）的形成引发的。由于减数分裂前的DNA复制导致每个同源物复制形成两个相同的姐妹染色单体，因此一个姐妹染色单体中的DSB可能使用另一个作为修复模板而不是同源物的两个非姐妹染色单体中的一个作为修复模板进行修复。如果这条途径占主导地位，交叉的形成将是不利的，染色体分离将受到损害。然而，在减数分裂期间，存在对同源物间重组（IHR）的强烈偏好。在这项研究中，我们鉴定了AtASY 3，它是拟南芥减数分裂期间组织染色体的蛋白质轴的组成部分。我们发现AtASY 3与AtASY 1相互作用，AtASY 1是一种先前确定的轴蛋白，对交叉形成至关重要。我们发现，AtASY 3的损失破坏了AtASY 1的轴组织。这导致交叉的大量减少，并且存在广泛的染色体错误分离。我们提出AtASY 3的缺失影响了同源物间偏倚的效率。
In this study we have analysed AtASY3, a coiled-coil domain protein that is required for normal meiosis in Arabidopsis. Analysis of an Atasy3-1 mutant reveals that loss of the protein compromises chromosome axis formation and results in reduced numbers of meiotic crossovers (COs). Although the frequency of DNA double-strand breaks (DSBs) appears moderately reduced in Atasy3-1, the main recombination defect is a reduction in the formation of COs. Immunolocalization studies in wild-type meiocytes indicate that the HORMA protein AtASY1, which is related to Hop1 in budding yeast, forms hyper-abundant domains along the chromosomes that are spatially associated with DSBs and early recombination pathway proteins. Loss of AtASY3 disrupts the axial organization of AtASY1. Furthermore we show that the AtASY3 and AtASY1 homologs BoASY3 and BoASY1, from the closely related species Brassica oleracea, are co-immunoprecipitated from meiocyte extracts and that AtASY3 interacts with AtASY1 via residues in its predicted coiled-coil domain. Together our results suggest that AtASY3 is a functional homolog of Red1. Since studies in budding yeast indicate that Red1 and Hop1 play a key role in establishing a bias to favor inter-homolog recombination (IHR), we propose that AtASY3 and AtASY1 may have a similar role in Arabidopsis. Loss of AtASY3 also disrupts synaptonemal complex (SC) formation. In Atasy3-1 the transverse filament protein AtZYP1 forms small patches rather than a continuous SC. The few AtMLH1 foci that remain in Atasy3-1 are found in association with the AtZYP1 patches. This is sufficient to prevent the ectopic recombination observed in the absence of AtZYP1, thus emphasizing that in addition to its structural role the protein is important for CO formation. Homologous recombination (HR) during prophase I of meiosis leads to the formation of physical connections, known as chiasmata, between homologous chromosomes (homologs). Chiasmata are essential for accurate homolog segregation at the first meiotic division. HR is initiated by the formation of DNA double-strand breaks (DSBs). As DNA replication prior to meiosis results in the duplication of each homolog to form two identical sister chromatids, a DSB in one sister chromatid could potentially be repaired using the other as the repair template rather than one of the two non-sister chromatids of the homolog. If this route were predominant, the formation of chiasmata would be disfavored and chromosome segregation would be compromised. However, during meiosis there is a strong bias towards inter-homolog recombination (IHR). In this study we have identified AtASY3, a component of the proteinaceous axes that organize the chromosomes during meiosis in Arabidopsis. We find that AtASY3 interacts with AtASY1, a previously identified axis protein that is essential for crossover formation. We show that loss of AtASY3 disrupts the axis-organization of AtASY1. This results in a substantial reduction in chiasmata, and there is extensive chromosome mis-segregation. We propose that loss of AtASY3 affects the efficiency of the inter-homolog bias.
登录
查看更多内容
影响因子：
7.2
作者：
Klimyuk, VI;Jones, JDG
通讯作者：
Jones, JDG
影响因子：
10.5
作者：
Gasior, SL;Wong, AK;Bishop, DK
通讯作者：
Bishop, DK
影响因子：
2.6
作者：
Lopez, Eva;Pradillo, Monica;Cunado, Nieves
通讯作者：
Cunado, Nieves
影响因子：
56.9
作者：
Alonso, JM;Stepanova, AN;Ecker, JR
通讯作者：
Ecker, JR
影响因子：
64.5
作者：
Blat, Y;Protacio, RU;Kleckner, N
通讯作者：
Kleckner, N