来自美国北卡罗来纳大学教堂山分校的研究人员发现蝇类中的微小染色体维持(MCM)蛋白进化获得促进减数分裂染色体重组的功能。

-2012年12月7日《科学》

中文翻译


【题目】蝇类MCM阻断BLM解旋酶的作用来促进减数分裂染色体交换

【译文】许多真核生物中减数分裂染色体交换的正常发生,需要借助Msh4-Msh5异二聚体来阻断解旋酶的去染色体交换活性。Msh4和Msh5在蝇类如果蝇(Drosophila)和舌蝇(Glossina)中长期缺失,但是我们鉴定到微小染色体维持(MCM)蛋白能在功能上取代Msh4-Msh5异二聚体。我们发现MCM8的直系同源物——REC蛋白,来源于一个先前未发现的后生动物特异性的MCM蛋白,它在蝇类的强阳性选择下进化,能与MEI-217及MEI-218互作。在果蝇recmei-217mei-218突变体中,减数分裂染色体交换程度减小;然而,若移除布卢姆综合症解旋酶(BLM)直系同源物,则能修复染色体交换。 总之,MCMs进化为一类新型复合物,MCMs能在果蝇中取代Msh4-Msh5异二聚体,发挥促进减数分裂染色体交换的功能。

英文原稿


[Title]: Evolution of an MCM Complex in Flies That Promotes Meiotic Crossovers by Blocking BLM Helicase  

[Authors]: Kathryn P. Kohl, Corbin D. Jones, and Jeff Sekelsky

[Abstract]: Generation of meiotic crossovers in many eukaryotes requires the elimination of anti-crossover activities by using the Msh4-Msh5 heterodimer to block helicases. Msh4 and Msh5 have been lost from the flies Drosophila and Glossina, but we identified a complex of minichromosome maintenance (MCM) proteins that functionally replace Msh4-Msh5. We found that REC, an ortholog of MCM8 that evolved under strong positive selection in flies, interacts with MEI-217 and MEI-218, which arose from a previously undescribed metazoan-specific MCM protein. Meiotic crossovers were reduced in Drosophila rec, mei-217, and mei-218 mutants; however, removal of the Bloom syndrome helicase (BLM) ortholog restored crossovers. Thus, MCMs were co-opted into a novel complex that replaced the meiotic pro-crossover function of Msh4-Msh5 in flies.

原文地址

http://www.sciencemag.org/content/338/6112/1363.abstract

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