Heo S J, Tatebayashi K, Kato J, Ikeda H
Department of Molecular Biology, University of Tokyo, Japan.
Mol Gen Genet. 1998 Jan;257(2):149-56. doi: 10.1007/s004380050634.
The Saccharomyces cerevisiae gene RHC21 is a homologue of the fission yeast rad21+ gene, which affects the sensitivity of cells to gamma-irradiation and is essential for cell growth in S. pombe. Disruption of the RHC21 gene showed that it is also essential in S. cerevisiae. To examine its function in cell growth further, we have isolated temperature-sensitive mutants for the RHC21 gene and characterized one of them, termed rhc21-sk16. When this mutant was incubated at 36 degrees C, the percentage of large-budded cells was increased. Most of the large-budded cells had aberrant nuclear structures, such as unequally extended nuclear DNA with incompletely elongated spindles across the mother-daughter neck or only in a mother cell. Furthermore, a circular minichromosome is more unstable in the mutant than in the wild-type, even at 25 degrees C. Flow cytometry showed that the bulk of DNA replication takes place normally at the restrictive temperature in the mutant. These results indicated that the RHC21 gene is required for proper segregation of the chromosomes. In addition, we found that the mutant is sensitive not only to UV radiation and gamma-rays but also to the antimicrotubule agent nocodazole at 25 degrees C. This suggests that the RHC21 gene is involved in the microtubule function. We discuss how the RHC21 gene product may be involved in chromosome segregation and microtubule function.
酿酒酵母基因RHC21是粟酒裂殖酵母rad21 +基因的同源物，该基因影响细胞对γ射线的敏感性，对粟酒裂殖酵母的细胞生长至关重要。RHC21基因的破坏表明它在酿酒酵母中也是必需的。为了进一步研究其在细胞生长中的功能，我们分离了RHC21基因的温度敏感突变体，并对其中一个名为rhc21 - sk16的突变体进行了表征。当这个突变体在36℃下培养时，大芽细胞的百分比增加。大多数大芽细胞具有异常的核结构，例如核DNA不均匀延伸，纺锤体在母-子颈部或仅在母细胞中不完全伸长。此外，即使在25℃下，环状微型染色体在突变体中也比在野生型中更不稳定。流式细胞术显示，在限制温度下，突变体中的大部分DNA复制正常进行。这些结果表明，RHC21基因是染色体正确分离所必需的。此外，我们发现该突变体不仅对紫外线辐射和γ射线敏感，而且在25℃下对抗微管药物诺考达唑也敏感。这表明RHC21基因参与微管功能。我们讨论了RHC21基因产物可能如何参与染色体分离和微管功能。
