p21-Activated Kinases Cla4 and Ste20 Regulate Vacuole Inheritance in Saccharomyces cerevisiae
p21-Activated Kinases Cla4 and Ste20 Regulate Vacuole Inheritance in Saccharomyces cerevisiae
复制标题
DOI：
10.1128/ec.00111-08
复制
发表时间：
2009-04-01
期刊：
影响因子：
--
通讯作者：
Hardy, Christopher F. J.
中科院分区：
文献类型：
--
作者：
Bartholomew, Clinton R.;Hardy, Christopher F. J.
每次酿酒酵母细胞分裂时，它们通过主动将液泡的一部分运送到芽中来确保母细胞和子细胞都继承一个液泡。当母细胞开始出芽时，形成管状和囊状分离结构，并通过肌凝蛋白V马达Myo2运输到芽中，Myo2与液泡特异性肌凝蛋白受体Vac17结合（41,59,70,79）。到达芽后，分离结构被分解，形成子液泡。以空间依赖的方式调节分离结构分辨率的机制尚不清楚。除了解决分离结构外，Vac17在芽中被特异性降解，为液泡遗传提供方向性。有人提出芽特异性降解Vac17是由定位于芽或仅在芽中激活的蛋白质促进的（77）。p21活化激酶（PAKs） cl4和Ste20定位于芽，并在芽中被激活。本文报道了cl4在分离结构分解之前定位于分离结构，缺乏PAK功能的细胞无法分解分离结构。过表达cl4或Ste20均可抑制液泡遗传，而这种抑制作用被不可降解的VAC17的表达所抑制。最后，在M期后期，Vac17降解需要PAK活性，而过表达cl4促进了Vac17的降解。我们认为cl4和Ste20是芽特异性蛋白，在分离结构分解和Vac17降解中都起作用。
Each time Saccharomyces cerevisiae cells divide they ensure that both the mother and daughter cell inherit a vacuole by actively transporting a portion of the vacuole into the bud. As the mother cell begins budding, a tubular and vesicular segregation structure forms that is transported into the bud by the myosin V motor Myo2, which is bound to the vacuole-specific myosin receptor, Vac17 (41, 59, 70, 79). Upon arriving in the bud the segregation structure is resolved to found the daughter vacuole. The mechanism that regulates segregation structure resolution in a spatially dependent manner is unknown. In addition to resolving the segregation structure, Vac17 is degraded specifically in the bud to provide directionality to vacuole inheritance. It has been proposed that bud-specific degradation of Vac17 is promoted by proteins localized to or activated solely in the bud (77). The p21-activated kinases (PAKs) Cla4 and Ste20 are localized to and activated in the bud. Here we report that Cla4 is localized to the segregation structure just prior to segregation structure resolution, and cells lacking PAK function fail to resolve the segregation structure. Overexpression of either Cla4 or Ste20 inhibited vacuole inheritance and this inhibition was suppressed by the expression of nondegradable VAC17. Finally, PAK activity was required for Vac17 degradation in late M phase and CLA4 overexpression promoted Vac17 degradation. We propose that Cla4 and Ste20 are bud-specific proteins that play roles in both segregation structure resolution and the degradation of Vac17.