title: Genetic study of the role of calcium ions in the cell division cycle of Saccharomyces cerevisiae: a calcium-dependent mutant and its trifluoperazine-dependent pseudorevertants.
abstract: 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.
mesh_terms: D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D002147:Calmodulin / Q000037:antagonists & inhibitors; D002453:Cell Cycle / Q000187:drug effects; D003433:Crosses, Genetic; D004271:DNA, Fungal / Q000235:genetics; D007700:Kinetics; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D014268:Trifluoperazine / Q000494:pharmacology*
chemical_list: D002147:Calmodulin; D004271:DNA, Fungal; D014268:Trifluoperazine; D002118:Calcium