The catalytically active tyrosine residues of both SPO11-1 and SPO11-2 are required for meiotic double-strand break induction in Arabidopsis
The catalytically active tyrosine residues of both SPO11-1 and SPO11-2 are required for meiotic double-strand break induction in Arabidopsis
复制标题
DOI：
10.1105/tpc.107.054817
复制
发表时间：
2007-10-01
期刊：
影响因子：
11.6
通讯作者：
Puchta, Holger
中科院分区：
文献类型：
--
作者：
Hartung, Frank;Wurz-Wildersinn, Rebecca;Puchta, Holger
SPO11是古细菌拓扑异构酶VI亚基a的同源物，在双链断裂（DSB）诱导的减数分裂重组起始中至关重要。与动物和酵母中的单一同源物相比，拟南芥和其他高等植物中存在三个同源物。虽然At SPO11-3参与体细胞内复制，但At SPO11-1和最近显示的At SPO11-2对于减数分裂重组的起始至关重要。进一步定义了At SPO11-2的作用，我们能够证明它是正确的染色体分离所必需的，因为它的缺失导致存活后代的非整倍体。双突变体SPO11-1与单突变体SPO11-2在表型上没有差异，这表明两种蛋白在同一步骤中都是必需的。与对At rad51-1单突变体的观察结果相反，SPO11-2和rad51-1的组合没有导致染色体断裂，这表明与SPO11- 1一样，SPO11-2也是诱导DSB所必需的。由于这两种SPO11突变体的减数分裂表型都可以通过全长基因的互补而逆转，而不是在各自催化活性Tyr中突变的相同结构，这两种蛋白质似乎都直接参与了DNA断裂反应。两个SPO11同源物对DSB形成的积极参与揭示了植物和其他真核生物在减数分裂中的显著差异。
SPO11, a homolog of the subunit A of the archaebacterial topoisomerase VI, is essential for double-strand break (DSB) induced initiation of meiotic recombination. In contrast with single homologs in animals and yeasts, three homologs are present in Arabidopsis thaliana and other higher plants. Whereas At SPO11-3 is involved in somatic endoreduplication, At SPO11-1 and, as recently shown, At SPO11-2 are essential for the initiation of meiotic recombination. Further defining the role of At SPO11-2, we were able to demonstrate that it is required for proper chromosome segregation, as its loss resulted in aneuploidy in the surviving progeny. The double mutant SPO11-1 SPO11-2 does not differ phenotypically from the single mutants, indicating that both proteins are required for the same step. Contrary to the observations for the At rad51-1 single mutant, the combination of SPO11-2 and rad51-1 did not lead to chromosome fragmentation, indicating that SPO11-2, like SPO11- 1, is required for DSB induction. As the meiotic phenotype of both single SPO11 mutants can be reversed by complementation using the full- length genes but not the same constructs mutated in their respective catalytically active Tyr, both proteins seem to participate directly in the DNA breakage reaction. The active involvement of two SPO11 homologs for DSB formation reveals a striking difference between plants and other eukaryotes in meiosis.