Synthetic lethal analysis implicates Ste20p, a p21-activated protein kinase, in polarisome activation
Synthetic lethal analysis implicates Ste20p, a p21-activated protein kinase, in polarisome activation
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DOI：
10.1091/mbc.e02-06-0348
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发表时间：
2003-04-01
影响因子：
3.3
通讯作者：
Sprague, GF
中科院分区：
文献类型：
--
作者：
Goehring, AS;Mitchell, DA;Sprague, GF
P21激活的激酶Ste20p和Cla4p在酿酒酵母的萌发过程中执行对生存至关重要的未知功能。为了深入了解Ste20p的作用，我们使用了合成的致命突变筛选来确定在缺少Cla4p的情况下所需的额外基因。我们总共鉴定了65个基因，包括与细胞极性、有丝分裂和细胞壁维持有关的基因。在这里，我们集中在一组定义了Bni1p及其几个相互作用的蛋白质执行的功能。我们发现Bni1p和一组与Bni1p复合的蛋白质(Bud6p、Spa2p和Pea2p)在Cla4Delta突变背景下是必不可少的。Bni1p、Bud6p、Spa2和Pea2p是一组被称为极化体的极性决定蛋白的成员。从Cla4Delta菌株中丢失极化体蛋白会导致细胞形成具有错位的隔素环的拉长的芽。相比之下，其他与Bni1p相互作用或在功能上与Bni1p相关并在核迁移和胞质分裂中发挥作用的蛋白质，包括Num1p和Hof1p，在缺少Cla4p的情况下并不是必需的。最后，我们发现Bni1p在体内被磷酸化，这种磷酸化的很大一部分依赖于STE20。综上所述，这些结果表明，Ste20p的一个功能可能是通过磷酸化Bni1p来激活极化体复合体。
The p21-activated kinases Ste20p and Cla4p carry out undefined functions that are essential for viability during budding in Saccharomyces cerevisiae. To gain insight into the roles of Ste20p, we have used a synthetic lethal mutant screen to identify additional genes that are required in the absence of Cla4p. Altogether, we identified 65 genes, including genes with roles in cell polarity, mitosis, and cell wall maintenance. Herein, we focus on a set that defines a function carried out by Bni1p and several of its interacting proteins. We found that Bni1p and a group of proteins that complex with Bni1p (Bud6p, Spa2p, and Pea2p) are essential in a cla4Delta mutant background. Bni1p, Bud6p, Spa2, and Pea2p are members of a group of polarity determining proteins referred to as the polarisome. Loss of polarisome proteins from a cla4Delta strain causes cells to form elongated buds that have mislocalized septin rings. In contrast, other proteins that interact with or functionally associate with Bni1p and have roles in nuclear migration and cytokinesis, including Num1p and Hof1p, are not essential in the absence of Cla4p. Finally, we have found that Bni1p is phosphorylated in vivo, and a substantial portion of this phosphorylation is dependent on STE20. Together, these results suggest that one function of Ste20p may be to activate the polarisome complex by phosphorylation of Bni1p.