Adaptor functions of Cdc42, Ste50, and Sho1 in the yeast osmoregulatory HOG MAPK pathway
Adaptor functions of Cdc42, Ste50, and Sho1 in the yeast osmoregulatory HOG MAPK pathway
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DOI：
10.1038/sj.emboj.7601192
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发表时间：
2006-07
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影响因子：
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通讯作者：
K. Tatebayashi;Katsuyoshi Yamamoto;Keiichiro Tanaka;T. Tomida;Takashi Maruoka;Eri Kasukawa;H. Saito
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文献类型：
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作者：
K. Tatebayashi;Katsuyoshi Yamamoto;Keiichiro Tanaka;T. Tomida;Takashi Maruoka;Eri Kasukawa;H. Saito
酵母高渗透压甘油（HOG）信号通路可以被两个上游通路（称为SHO 1和SLN 1分支）中的任一个激活。当被高渗透压刺激时，SHO 1分支激活由Ste 11 MAPKKK、Pbs 2 MAPKK和Hog 1 MAPK组成的MAP激酶模块。为了研究应激如何激活该MAPK模块，我们分离了SHO 1分支中涉及的四个关键基因中的功能获得和功能丧失等位基因，即SHO 1，CDC 42，STE 50和STE 11。使用HOG依赖性报告基因8xCRE-lacZ表征这些突变体。我们发现Cdc 42除了结合和激活PAK样激酶Ste 20和Cla 4外，还结合Ste 11-Ste 50复合物，将激活的Ste 20/Cla 4带到其底物Ste 11。激活的Ste 11及其HOG途径特异性底物Pbs 2通过Sho 1结合在一起; Ste 11-Ste 50复合物与Sho 1的胞质结构域结合，Pbs 2也与Sho 1结合。因此，Cdc 42，Ste 50和Sho 1作为衔接蛋白，控制着从Ste 20/Cla 4到Ste 11，然后到Pbs 2的胁迫信号流。
The yeast high osmolarity glycerol (HOG) signaling pathway can be activated by either of the two upstream pathways, termed the SHO1 and SLN1 branches. When stimulated by high osmolarity, the SHO1 branch activates an MAP kinase module composed of the Ste11 MAPKKK, the Pbs2 MAPKK, and the Hog1 MAPK. To investigate how osmostress activates this MAPK module, we isolated both gain‐of‐function and loss‐of‐function alleles in four key genes involved in the SHO1 branch, namelySHO1,CDC42,STE50, andSTE11. These mutants were characterized using an HOG‐dependent reporter gene,8xCRE‐lacZ. We found that Cdc42, in addition to binding and activating the PAK‐like kinases Ste20 and Cla4, binds to the Ste11–Ste50 complex to bring activated Ste20/Cla4 to their substrate Ste11. Activated Ste11 and its HOG pathway‐specific substrate, Pbs2, are brought together by Sho1; the Ste11–Ste50 complex binds to the cytoplasmic domain of Sho1, to which Pbs2 also binds. Thus, Cdc42, Ste50, and Sho1 act as adaptor proteins that control the flow of the osmostress signal from Ste20/Cla4 to Ste11, then to Pbs2.