RELATIONSHIP BETWEEN EXTRACELLULAR ENZYMES AND CELL GROWTH DURING THE CELL CYCLE OF THE FISSION YEAST SCHIZOSACCHAROMYCES POMBE

[摘要] By using intact cells of the fission yeast Schizosaccharomyces pombe, the derepressed activity of sucrase (EC 3. 2. 1.26), as extracellular enzyme located in the periphery of the yeast, was measured during the cell cycle, with cell length serving as the measure of cell growth. Both specific activity of sucrase and average cell length were constant through asynchronous cultures. Under the same experimental conditions as for asynchronous cultures, the specific activity of sucrase showed a pattern of periodic synthesis after either selection synchronization by the gradient sedimentation method or induction synchronization by pulse treatment with hydroxyurea (HU), an inhibitor of DNA synthesis. On the other hand, the specific activity of sucrase continued to increase exponentially when HU was added to the asynchronous culture or to the selection-synchronous culture, but decreased stepwise in induction- synchronous cultures in a poor medium after selection, in which the cells divided synchronously without cell elongation. The patterns of sucrase activity in all systems were parallel to those for average cell length.These results suggest that the synthesis of sucrase is dependent on the growth in cell length as well as acid phosphatase as we reported in a previous paper (1).

[学科分类] 微生物学和免疫学