Johnston L H, Eberly S L, Chapman J W, Araki H, Sugino A
Laboratory of Cell Propagation, National Institute for Medical Research, Mill Hill, London.
Mol Cell Biol. 1990 Apr;10(4):1358-66. doi: 10.1128/mcb.10.4.1358-1366.1990.
Several Saccharomyces cerevisiae dbf mutants defective in DNA synthesis have been described previously. In this paper, one of them, dbf2, is characterized in detail. The DBF2 gene has been cloned and mapped, and its nucleotide sequence has been determined. This process has identified an open reading frame capable of encoding a protein of molecular weight 64,883 (561 amino acids). The deduced amino acid sequence contains all 11 conserved domains found in various protein kinases. DBF2 was periodically expressed in the cell cycle at a time that clearly differed from the time of expression of either the histone H2A or DNA polymerase I gene. Its first function was completed very near to initiation of DNA synthesis. However, DNA synthesis in the mutant was only delayed at 37 degrees C, and the cells blocked in nuclear division. Consistent with this finding, the execution point occurred about 1 h after DNA synthesis, and the nuclear morphology of the mutant at the restrictive temperature was that of cells blocked in late nuclear division. DBF2 is therefore likely to encode a protein kinase that may function in initiation of DNA synthesis and also in late nuclear division.
先前已描述了几种在DNA合成方面存在缺陷的酿酒酵母dbf突变体。在本文中，对其中一个突变体dbf2进行了详细表征。DBF2基因已被克隆和定位，并确定了其核苷酸序列。这一过程鉴定出一个开放阅读框，能够编码一种分子量为64,883（561个氨基酸）的蛋白质。推导的氨基酸序列包含在各种蛋白激酶中发现的所有11个保守结构域。DBF2在细胞周期中周期性表达，其时间明显不同于组蛋白H2A或DNA聚合酶I基因的表达时间。它的首要功能在非常接近DNA合成起始时完成。然而，突变体中的DNA合成仅在37℃时延迟，细胞在核分裂中受阻。与这一发现一致，执行点发生在DNA合成后约1小时，在限制温度下突变体的核形态是处于核分裂后期受阻的细胞的形态。因此，DBF2可能编码一种蛋白激酶，其可能在DNA合成起始以及核分裂后期发挥作用。
