Ohya Y, Ohsumi Y, Anraku Y
Mol Gen Genet. 1984;193(3):389-94. doi: 10.1007/BF00382073.
A cal1-1 mutant of the yeast Saccharomyces cerevisiae showing Ca2+-dependent growth was isolated. Its growth continued exponentially in Ca2+-rich medium, but stopped in Ca2+-poor medium at 37 degrees C. Mg2+ ions could not replace Ca2+ ions. In Ca2+-poor medium, the mutant cells stopped growing homogeneously at the stage of cell division cycle with a tiny bud. The nucleus in these arrested cells was in the G2 stage, judging from observation after nuclear staining and determination of the DNA content. Trifluoperazine-dependent pseudorevertants, which could grow in the presence of 20 microM to 80 microM trifluoperazine in Ca2+-poor medium at 37 degrees C, were obtained from this cal1-1 mutant. The suppressor mutation, tfr1, itself conferred trifluoperazine resistance. Other calmodulin inhibitors structurally unrelated to trifluoperazine had similar effects to trifluoperazine on these pseudorevertants. These results suggest that Ca2+ ions and a calmodulin play important roles in the yeast cell division cycle at the stage of bud growth and nuclear division.
分离出了酿酒酵母的一个钙调磷酸酶1-1（cal1-1）突变体，其生长表现出钙依赖性。它在富含钙离子的培养基中呈指数级持续生长，但在37℃的低钙培养基中停止生长。镁离子不能替代钙离子。在低钙培养基中，突变细胞在带有微小芽的细胞分裂周期阶段均匀地停止生长。从核染色后的观察结果和DNA含量测定判断，这些停滞细胞中的细胞核处于G2期。从这个cal1-1突变体中获得了三氟拉嗪依赖性假回复体，它们在37℃的低钙培养基中，在20微摩尔至80微摩尔三氟拉嗪存在的情况下能够生长。抑制突变tfr1本身赋予了对三氟拉嗪的抗性。其他与三氟拉嗪结构不相关的钙调蛋白抑制剂对这些假回复体具有与三氟拉嗪类似的作用。这些结果表明，钙离子和一种钙调蛋白在酵母细胞分裂周期的芽生长和核分裂阶段发挥重要作用。
