Leem S H, Chung C N, Sunwoo Y, Araki H
Department of Biochemistry and Molecular Biology, Research Institute for Microbial Diseases, Osaka University, Yamada-oka 3-1, Suita, Osaka 565-0871, Japan.
Nucleic Acids Res. 1998 Jul 1;26(13):3154-8. doi: 10.1093/nar/26.13.3154.
The transcript levels of DNA replication genes and some recombination genes in Saccharomyces cerevisiae fluctuate and peak at the G1/S boundary in the mitotic cell cycle. This fluctuation is regulated by MCB (Mlu I cell cycle box) elements which are bound by the DSC1/MBF1 complex consisting of Swi6 and Mbp1. It is also known that some of the MCB-regulated genes are induced by treatment with DNA damaging agents and in meiosis. In this report, the function of SWI6 in meiosis was investigated. Delta swi6 cells underwent sporulation as did wild-type cells. However, the deletion mutant cells showed reduced spore viability and lower frequency of recombination. The transcript levels of the recombination genes RAD51 and RAD54 , which have MCB elements, were reduced in Delta swi6 cells. The transcript levels of SWI6 itself were also induced and declined in meiosis. Furthermore, an increased dosage of SWI6 enhanced the transcript level of the RAD51 gene and also the recombination frequency in meiosis. These results suggest that SWI6 enhances the expression level of the recombination genes in meiosis in a dosage-dependent manner, which results in an effect on the frequency of meiotic recombination.
酿酒酵母中DNA复制基因和一些重组基因的转录水平在有丝分裂细胞周期的G1/S边界处波动并达到峰值。这种波动由MCB（Mlu I细胞周期框）元件调控，该元件由Swi6和Mbp1组成的DSC1/MBF1复合物结合。还已知一些受MCB调控的基因在DNA损伤剂处理和减数分裂过程中被诱导。在本报告中，研究了SWI6在减数分裂中的功能。Δswi6细胞与野生型细胞一样进行孢子形成。然而，缺失突变细胞的孢子活力降低，重组频率也较低。具有MCB元件的重组基因RAD51和RAD54在Δswi6细胞中的转录水平降低。SWI6自身的转录水平在减数分裂中也被诱导并下降。此外，增加SWI6的剂量可提高RAD51基因的转录水平以及减数分裂中的重组频率。这些结果表明，SWI6以剂量依赖的方式增强减数分裂中重组基因的表达水平，从而对减数分裂重组频率产生影响。
