Génétique, Reproduction et Développement, UMR CNRS 6293 - Clermont Université - INSERM U1103, Aubière, France.
PLoS Genet. 2013;9(9):e1003787. doi: 10.1371/journal.pgen.1003787. Epub 2013 Sep 26.
Recombination establishes the chiasmata that physically link pairs of homologous chromosomes in meiosis, ensuring their balanced segregation at the first meiotic division and generating genetic variation. The visible manifestation of genetic crossing-overs, chiasmata are the result of an intricate and tightly regulated process involving induction of DNA double-strand breaks and their repair through invasion of a homologous template DNA duplex, catalysed by RAD51 and DMC1 in most eukaryotes. We describe here a RAD51-GFP fusion protein that retains the ability to assemble at DNA breaks but has lost its DNA break repair capacity. This protein fully complements the meiotic chromosomal fragmentation and sterility of Arabidopsis rad51, but not rad51 dmc1 mutants. Even though DMC1 is the only active meiotic strand transfer protein in the absence of RAD51 catalytic activity, no effect on genetic map distance was observed in complemented rad51 plants. The presence of inactive RAD51 nucleofilaments is thus able to fully support meiotic DSB repair and normal levels of crossing-over by DMC1. Our data demonstrate that RAD51 plays a supporting role for DMC1 in meiotic recombination in the flowering plant, Arabidopsis.
重组建立了在减数分裂中物理连接同源染色体对的交叉，确保它们在第一次减数分裂中的平衡分离，并产生遗传变异。交叉的可见表现是一个复杂而严格调控的过程的结果，涉及到 DNA 双链断裂的诱导，以及通过 RAD51 和 DMC1 在大多数真核生物中催化的同源模板 DNA 双链的入侵进行修复。我们在这里描述了一种 RAD51-GFP 融合蛋白，它保留了在 DNA 断裂处组装的能力，但失去了 DNA 断裂修复能力。这种蛋白完全互补了拟南芥 rad51 的减数分裂染色体碎片化和不育，但不能互补 rad51 dmc1 突变体。尽管 DMC1 是在没有 RAD51 催化活性的情况下唯一活跃的减数分裂链转移蛋白，但在互补的 rad51 植物中，遗传图谱距离没有观察到影响。因此，无活性的 RAD51 核纤丝能够完全支持减数分裂 DSB 的修复和 DMC1 介导的正常交叉频率。我们的数据表明，RAD51 在拟南芥的有性生殖重组中为 DMC1 提供支持作用。
