Fox M E, Smith G R
Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.
Prog Nucleic Acid Res Mol Biol. 1998;61:345-78. doi: 10.1016/s0079-6603(08)60831-4.
Homologous recombination occurs at high frequency during meiosis and is essential for the proper segregation of chromosomes and the generation of genetic diversity. Meiotic recombination is controlled in numerous ways. In the fission yeast Schizosaccharomyces pombe nutritional starvation induces meiosis and high-level expression of many genes, including numerous recombination (rec) genes, whose products are required for recombination. Accompanying the two meiotic divisions are profound changes in nuclear and chromosomal structure and movement, which may play an important role in meiotic recombination. Although recombination occurs throughout the genome, it occurs at high frequency in some intervals (hotspots) and at low frequency in others (coldspots). The well-characterized hotspot M26 is activated by the Mts1/Mts2 protein; this site and its binding proteins interact with the local chromosomal structure to enhance recombination. A coldspot between the silent mating-type loci is repressed by identified proteins, which may also alter local chromatin. We discuss in detail the rec genes and the possible functions of their products, some but not all of which share homology with other identified proteins. Although some of the rec gene products are required for recombination throughout the genome, others demonstrate regional specificity and are required in certain genomic regions but not in others. Throughout the review contrasts are made with meiotic recombination in the more thoroughly studied budding yeast Saccharomyces cerevisiae.
同源重组在减数分裂期间高频发生，对于染色体的正确分离和遗传多样性的产生至关重要。减数分裂重组受到多种方式的调控。在裂殖酵母粟酒裂殖酵母中，营养饥饿会诱导减数分裂以及许多基因的高水平表达，包括众多重组（rec）基因，其产物是重组所必需的。伴随两次减数分裂的是核和染色体结构及运动的深刻变化，这可能在减数分裂重组中起重要作用。尽管重组发生在整个基因组中，但在某些区间（热点）高频发生，而在其他区间（冷点）低频发生。特征明确的热点M26由Mts1/Mts2蛋白激活；该位点及其结合蛋白与局部染色体结构相互作用以增强重组。沉默交配型位点之间的一个冷点被已鉴定的蛋白质抑制，这些蛋白质也可能改变局部染色质。我们详细讨论rec基因及其产物的可能功能，其中一些但并非全部与其他已鉴定的蛋白质具有同源性。尽管一些rec基因产物是整个基因组重组所必需的，但其他一些则表现出区域特异性，仅在某些基因组区域而非其他区域需要。在整个综述中，我们将与研究更深入的芽殖酵母酿酒酵母中的减数分裂重组进行对比。
