Zhang Lei, Tang Ding, Luo Qiong, Chen Xiaojun, Wang Hongjun, Li Yafei, Cheng Zhukuan
State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
Ministry of Education Key Laboratory of Agriculture Biodiversity for Plant Disease Management, Yunnan Agricultural University, Kunming 650201, China.
Genetics. 2014 Dec;198(4):1447-56. doi: 10.1534/genetics.114.168732. Epub 2014 Oct 2.
MSH4 encodes a MutS protein that plays a specialized role in meiosis. In eukaryotic species, such as budding yeast, mice, Caenorhabditis elegans, and Arabidopsis, msh4 mutants display meiotic defects with a reduced number of chiasmata. Here, we characterized rice MSH4 by map-based cloning. In Osmsh4 mutants, the chiasma frequency was dramatically decreased to ∼10% of the wild type, but the synaptonemal complex was normally installed. The double mutant analysis showed that in the Osmsh4 Osmsh5 mutant, the reduction of chiasmata was greater than other zmm mutants. This was consistent with the absence of localization for OsZIP4 and OsMER3 in Osmsh4 and suggests an earlier role for OsMSH4 and OsMSH5 than other ZMM proteins where they may be required to stabilize progenitor Holliday junctions. Using yeast two-hybrid and pull-down assays, we verified the direct physical association between OsMSH4 and OsMSH5 and OsMSH5 and HEI10 in plants for the first time. The MSH4-MSH5 heterodimer has been demonstrated in mammals to stabilize the formation of progenitor and double Holliday junctions that may be resolved as crossovers (COs). We propose that OsMSH4 interacts with OsMSH5 to promote formation of the majority of COs in rice.
MSH4编码一种在减数分裂中起特殊作用的MutS蛋白。在真核生物物种中，如芽殖酵母、小鼠、秀丽隐杆线虫和拟南芥，msh4突变体表现出减数分裂缺陷，交叉数减少。在这里，我们通过图位克隆对水稻MSH4进行了表征。在Osmsh4突变体中，交叉频率显著降低至野生型的~10%，但联会复合体正常形成。双突变分析表明，在Osmsh4 Osmsh5突变体中，交叉减少比其他zmm突变体更严重。这与Osmsh4中OsZIP4和OsMER3的定位缺失一致，表明OsMSH4和OsMSH5比其他ZMM蛋白发挥更早的作用，它们可能需要稳定祖源霍利迪连接体。通过酵母双杂交和下拉试验，我们首次在植物中验证了OsMSH4与OsMSH5以及OsMSH5与HEI10之间的直接物理相互作用。在哺乳动物中，MSH4-MSH5异二聚体已被证明可稳定祖源和双霍利迪连接体的形成，这些连接体可能会被解析为交叉（COs）。我们提出，OsMSH4与OsMSH5相互作用以促进水稻中大多数COs的形成。
