A Unique DNA Recombination Mechanism of the Mating/Cell-type Switching of Fission Yeasts: a Review.
A Unique DNA Recombination Mechanism of the Mating/Cell-type Switching of Fission Yeasts: a Review.
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DOI：
10.1128/microbiolspec.mdna3-0003-2014
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发表时间：
2014-10
影响因子：
3.7
通讯作者：
Moore S
中科院分区：
文献类型：
--
作者：
Klar AJS;Ishikawa K;Moore S
高度分化的裂殖酵母（S.）pombe和S.双分裂酵母存在于两种性别/交配类型中的一种，称为P（正）或M（负），由等位基因M或P位于mat 1指定。裂变酵母已经进化出一种优雅的机制，通过程序化的DNA重组事件，与基因组中邻近的两个沉默交配型基因之一的拷贝交换mat 1上的P或M信息。转换过程是高度细胞周期和世代依赖性的，使得细胞的四个孙子中只有一个转换交配类型。对裂殖酵母的广泛研究确立了在mat 1位点的天然DNA链手性作为不对称细胞分裂的主要基础。这种不对称性是由DNA复制过程中两个染色单体之一的mat 1上的一个独特的位点和链特异性表观遗传“印记”造成的。印记由一个子细胞继承，维持一个细胞周期，然后用于在下一个细胞周期中的mat 1复制期间启动重组。这种细胞类型转换的机制被认为是这两种生物体所特有的，但由于技术原因，在其他生物体中确定这种机制的运作是不可能的。这篇综述总结了最近令人兴奋的发展，在裂变酵母中的交配型开关的理解，并扩展这些观察，建议如何这样的DNA链为基础的细胞分化的表观遗传机制也可以在二倍体生物体。
Cells of the highly diverged Schizosaccharomyces (S.) pombe and S. japonicus fission yeasts exist in one of two sex/mating types, called P (for plus) or M (for minus), specified by which allele, M or P, resides at mat1. The fission yeasts have evolved an elegant mechanism for switching P or M information at mat1 by a programmed DNA recombination event with a copy of one of the two silent mating-type genes residing nearby in the genome. The switching process is highly cell-cycle and generation dependent such that only one of four grandchildren of a cell switches mating type. Extensive studies of fission yeast established the natural DNA strand chirality at the mat1 locus as the primary basis of asymmetric cell division. The asymmetry results from a unique site- and strand-specific epigenetic “imprint” at mat1 installed in one of the two chromatids during DNA replication. The imprint is inherited by one daughter cell, maintained for one cell cycle, and is then used for initiating recombination during mat1 replication in the following cell cycle. This mechanism of cell-type switching is considered to be unique to these two organisms, but determining the operation of such a mechanism in other organisms has not been possible for technical reasons. This review summarizes recent exciting developments in the understanding of mating-type switching in fission yeasts and extends these observations to suggest how such a DNA strand-based epigenetic mechanism of cellular differentiation could also operate in diploid organisms.