Sugano S, Shobuike T, Takeda T, Sugino A, Ikeda H
Department of Molecular Biology, University of Tokyo, Japan.
Mol Gen Genet. 1994 Apr;243(1):1-8. doi: 10.1007/BF00283869.
The DST2 gene of Saccharomyces cerevisiae encodes a DNA strand exchange protein, STP beta, which is required for homologous recombination in both mitotic or meiotic cells. We have cloned a DST2-related gene from the fission yeast Schizosaccharomyces pombe and designated it dhp1+. The nucleotide sequence of dhp1+ revealed an open reading frame encoding a protein composed of 991 amino acids. The predicted amino acid sequence was significantly homologous to the S. cerevisiae STP beta, but lacked the carboxy-terminal sequence present in STP beta. Furthermore, dhp1+ shows greater homology to RAT1/HKE1, a gene which is involved in RNA trafficking and processing. Genetic experiments showed that dhp1+ on an S. cerevisiae expression vector could rescue both the defects of the S. cerevisiae DST2 disruptant, slow growth rate and a sporulation defect, and the lethality of the S. cerevisiae rat1ts mutation. This implies the functional similarity of dhp1+ to both DST2 and RAT1. However unlike DST2, dhp1+ is an essential gene for cell growth in S. pombe, suggesting that dhp1+ is not the true homologue of DST2 but rather of RAT1 in S. pombe. The possible roles of dhp1+ in recombination and cell growth in S. pombe are discussed.
酿酒酵母的DST2基因编码一种DNA链交换蛋白STPβ，它是有丝分裂或减数分裂细胞中同源重组所必需的。我们从裂殖酵母粟酒裂殖酵母中克隆了一个与DST2相关的基因，并将其命名为dhp1+。dhp1+的核苷酸序列揭示了一个编码由991个氨基酸组成的蛋白质的开放阅读框。预测的氨基酸序列与酿酒酵母的STPβ具有显著的同源性，但缺少STPβ中存在的羧基末端序列。此外，dhp1+与参与RNA运输和加工的基因RAT1/HKE1具有更高的同源性。遗传实验表明，酿酒酵母表达载体上的dhp1+可以挽救酿酒酵母DST2破坏株的两种缺陷，即生长速率缓慢和孢子形成缺陷，以及酿酒酵母rat1ts突变的致死性。这意味着dhp1+与DST2和RAT1在功能上具有相似性。然而，与DST2不同的是，dhp1+是粟酒裂殖酵母细胞生长所必需的基因，这表明dhp1+不是DST2的真正同源物，而是粟酒裂殖酵母中RAT1的同源物。本文讨论了dhp1+在粟酒裂殖酵母重组和细胞生长中的可能作用。
