Tatebayashi K, Tani T, Ikeda H
Department of Molecular Biology, Institute of Medical Science, the University of Tokyo, P.O. Takanawa, Tokyo 108-8639, Japan.
Genetics. 2001 Apr;157(4):1513-22. doi: 10.1093/genetics/157.4.1513.
We have cloned and characterized the Schizosaccharomyces pombe gene mog1(+), which encodes a protein with homology to the Saccharomyces cerevisiae Mog1p participating in the Ran-GTPase system. The S. pombe Mog1p is predominantly localized in the nucleus. In contrast to the S. cerevisiae MOG1 gene, the S. pombe mog1(+) gene is essential for cell viability. mog1(+) is required for the mitosis-to-interphase transition, as the mog1-1 mutant arrests at restrictive temperatures as septated, binucleated cells with highly condensed chromosomes and an aberrant nuclear envelope. FACS analysis showed that these cells do not undergo a subsequent round of DNA replication. Surprisingly, also unlike the Delta mog1 mutation in S. cerevisiae, the mog1-1 mutation causes nucleolar accumulation of poly(A)(+) RNA at the restrictive temperature in S. pombe, but the signals do not overlap with the fibrillarin-rich region of the nucleolus. Thus, we found that mog1(+) is required for the mitosis-to-interphase transition and a class of RNA metabolism. In our attempt to identify suppressors of mog1-1, we isolated the spi1(+) gene, which encodes the fission yeast homologue of Ran. We found that overexpression of Spi1p rescues the S. pombe Delta mog1 cells from death. On the basis of these results, we conclude that mog1(+) is involved in the Ran-GTPase system.
我们已经克隆并鉴定了粟酒裂殖酵母基因mog1(+)，该基因编码一种与参与Ran - GTP酶系统的酿酒酵母Mog1p具有同源性的蛋白质。粟酒裂殖酵母Mog1p主要定位于细胞核。与酿酒酵母MOG1基因不同，粟酒裂殖酵母mog1(+)基因对细胞活力至关重要。mog1(+)是有丝分裂到间期转变所必需的，因为mog1 - 1突变体在限制温度下停滞为分隔的双核细胞，染色体高度浓缩且核膜异常。流式细胞术分析表明这些细胞不会进行随后的一轮DNA复制。令人惊讶的是，与酿酒酵母中的Δmog1突变也不同，mog1 - 1突变在限制温度下导致粟酒裂殖酵母中聚腺苷酸(+)RNA在核仁积累，但信号与富含纤维蛋白原的核仁区域不重叠。因此，我们发现mog1(+)是有丝分裂到间期转变和一类RNA代谢所必需的。在我们试图鉴定mog1 - 1的抑制子时，我们分离出了spi1(+)基因，该基因编码Ran的裂殖酵母同源物。我们发现Spi1p的过表达拯救了粟酒裂殖酵母Δmog1细胞免于死亡。基于这些结果，我们得出结论，mog1(+)参与Ran - GTP酶系统。
