Hata H, Mitsui H, Liu H, Bai Y, Denis C L, Shimizu Y, Sakai A
Cellular Signaling Group, Mitsubishi Kasei Institute of Life Sciences, Tokyo, Japan.
Genetics. 1998 Feb;148(2):571-9. doi: 10.1093/genetics/148.2.571.
The POP2 (Caf1) protein in Saccharomyces cerevisiae affects a variety of transcriptional processes and is a component of the Ccr4p complex. We have isolated five multicopy suppressor genes of a pop2 deletion mutation: CCR4, DHH1 (a putative RNA helicase), PKC1, STM1, and MPT5 (multicopy suppressor of pop two). Overexpression of either the CCR4 or DHH1 genes effectively suppressed phenotypes associated with pop2 mutant cells; overexpression of PKC1, STM1, or MPT5 genes produced only partial suppression. Disruption of the CCR4 or DHH1 genes resulted in phenotypes similar to those observed for pop2 cells. In addition, overexpression of the DHH1 gene also suppressed the ccr4 mutation, suggesting a close relationship between the POP2, CCR4, and DHH1 genes. Two-hybrid analysis and coimmunoprecipitation experiments revealed that Pop2p and Dhh1p interact physically, and these and other data suggest that Dhh1p is also a component of the Ccr4p complex. Finally, we investigated the genetic interaction between factors associated with POP2 and the PKC1 pathway. The temperature-sensitive growth defect of dhh1 or mpt5 cells was suppressed by overexpression of PKC1, and the defect of mpk1 cells was suppressed by overexpression of MPT5. These results and phenotypic analysis of double mutants from the POP2 and PKC1 pathways suggested that the POP2 and the PKC1 pathways are independent but have some overlapping functions.
酿酒酵母中的POP2（Caf1）蛋白影响多种转录过程，是Ccr4p复合物的一个组成部分。我们分离出了pop2缺失突变的五个多拷贝抑制基因：CCR4、DHH1（一种假定的RNA解旋酶）、PKC1、STM1和MPT5（pop2的多拷贝抑制子）。CCR4或DHH1基因的过表达有效抑制了与pop2突变细胞相关的表型；PKC1、STM1或MPT5基因的过表达仅产生部分抑制。CCR4或DHH1基因的破坏导致了与pop2细胞中观察到的类似表型。此外，DHH1基因的过表达也抑制了ccr4突变，表明POP2、CCR4和DHH1基因之间存在密切关系。双杂交分析和免疫共沉淀实验表明Pop2p和Dhh1p存在物理相互作用，这些以及其他数据表明Dhh1p也是Ccr4p复合物的一个组成部分。最后，我们研究了与POP2相关的因子和PKC1途径之间的遗传相互作用。PKC1的过表达抑制了dhh1或mpt5细胞的温度敏感生长缺陷，MPT5的过表达抑制了mpk1细胞的缺陷。这些结果以及来自POP2和PKC1途径的双突变体表型分析表明，POP2和PKC1途径是独立的，但具有一些重叠功能。
