Yeast spore germination: a requirement for Ras protein activity during re-entry into the cell cycle
Yeast spore germination: a requirement for Ras protein activity during re-entry into the cell cycle
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DOI：
10.1093/emboj/16.20.6171
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发表时间：
1997-10-15
期刊：
影响因子：
11.4
通讯作者：
Rine, J
中科院分区：
文献类型：
--
作者：
Herman, PK;Rine, J
酿酒酵母孢子萌发是一个过程，其中静止的、不分裂的孢子变得能够进行有丝分裂细胞分裂。使用一种新颖的孢子脱壳测定法，我们发现孢子萌发是一个多步骤的过程，其营养要求与有丝分裂分裂的营养要求不同。尽管这两个过程都受到营养可用性的控制，但在不支持细胞分裂的条件下发生有效的孢子萌发。此外，萌发 不需要许多细胞周期进程的关键调节因子，包括细胞周期蛋白依赖性激酶 Cdc28p，然而，孢子萌发需要细胞生长必需的两个过程，即蛋白质合成和通过 Ras 蛋白途径的信号传导。此外，孢子中 Ras 蛋白活性的增加导致萌发速率加快，表明 Ras 途径的激活是进入萌发程序的速率限制。发芽的早期步骤，定型，被确定为孢子不可逆地注定要完成脱壳过程的点，即使最初的发芽刺激被去除，孢子对发芽的定型需要蛋白质合成和Ras蛋白活性；相比之下，承诺后事件不需要持续的蛋白质合成。总而言之，这些数据提出了在静止期和细胞周期进展之间的过渡期间 Ras 功能的模型。
Saccharomyces cerevisiae spore germination is a process in which quiescent, non-dividing spores become competent for mitotic cell division, Using a novel assay for spore uncoating, we found that spore germination was a multi-step process whose nutritional requirements differed from those for mitotic division, Although both processes were controlled by nutrient availability, efficient spore germination occurred in conditions that did not support cell division, In addition, germination did not require many key regulators of cell cycle progression including the cyclin-dependent kinase, Cdc28p, However, two processes essential for cell growth, protein synthesis and signaling through the Ras protein pathway, were required for spore germination, Moreover, increasing Ras protein activity in spores resulted in an accelerated rate of germination and suggested that activation of the Ras pathway was rate-limiting for entry into the germination program. An early step in germination, commitment, was identified as the point at which spores became irreversibly destined to complete the uncoating process even if the original stimulus for germination was removed, Spore commitment to germination required protein synthesis and Ras protein activity; in contrast, post-commitment events did not require ongoing protein synthesis, Altogether, these data suggested a model for Ras function during transitions between periods of quiescence and cell cycle progression.