Takahashi K, Yamada H, Yanagida M
Department of Biophysics, Faculty of Science, Kyoto University, Japan.
Mol Biol Cell. 1994 Oct;5(10):1145-58. doi: 10.1091/mbc.5.10.1145.
Precise chromosome transmission in cell division cycle is maintained by a number of genes. The attempt made in the present study was to isolate temperature-sensitive (ts) fission yeast mutants that display high loss rates of minichromosomes at permissive or semipermissive temperature (designated mis). By colony color assay of 539 ts strains that contain a minichromosome, we have identified 12 genetic loci (mis1-mis12) and determined their phenotypes at restrictive temperature. Seven of them are related to cell cycle block phenotype at restrictive temperature, three of them in mitosis. Unequal distribution of regular chromosomes in the daughters is extensive in mis6 and mis12. Cells become inviable after rounds of cell division due to missegregation. The phenotype of mis5 is DNA replication defect and hypersensitivity to UV ray and hydroxyurea. mis5+ encodes a novel member of the ubiquitous MCM family required for the onset of replication. The mis5+ gene is essential for viability and functionally distinct from other previously identified members in fission yeast, cdc21+, nda1+, and nda4+. The mis11 mutant phenotype was the cell division block with reduced cell size. Progression of the G1 and G2 phases is blocked in mis11. The cloned mis11+ gene is identical to prp2+, which is essential for RNA splicing and similar to a mammalian splicing factor U2AF65.
细胞分裂周期中精确的染色体传递由许多基因维持。本研究的目的是分离出在允许温度或半允许温度下显示出高频率小染色体丢失率的温度敏感（ts）裂殖酵母突变体（命名为mis）。通过对539个含有小染色体的ts菌株进行菌落颜色测定，我们鉴定出了12个基因位点（mis1 - mis12），并确定了它们在限制温度下的表型。其中7个与限制温度下的细胞周期阻滞表型有关，3个与有丝分裂有关。在mis6和mis12中，子代中常规染色体的不均等分布很广泛。由于错误分离，细胞在几轮细胞分裂后变得无法存活。mis5的表型是DNA复制缺陷以及对紫外线和羟基脲超敏。mis5 +编码一种在复制起始时所需的普遍存在的MCM家族的新成员。mis5 +基因对于生存力至关重要，并且在功能上与裂殖酵母中先前鉴定的其他成员cdc21 +、nda1 +和nda4 +不同。mis11突变体表型是细胞分裂阻滞且细胞尺寸减小。在mis11中，G1期和G2期的进程被阻断。克隆的mis11 +基因与prp2 +相同，prp2 +对于RNA剪接至关重要，并且与哺乳动物剪接因子U2AF65相似。
