Chang M, French-Cornay D, Fan H Y, Klein H, Denis C L, Jaehning J A
Department of Biochemistry and Molecular Genetics and Program in Molecular Biology, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
Mol Cell Biol. 1999 Feb;19(2):1056-67. doi: 10.1128/MCB.19.2.1056.
Yeast contains at least two complex forms of RNA polymerase II (Pol II), one including the Srbps and a second biochemically distinct form defined by the presence of Paf1p and Cdc73p (X. Shi et al., Mol. Cell. Biol. 17:1160-1169, 1997). In this work we demonstrate that Ccr4p and Hpr1p are components of the Paf1p-Cdc73p-Pol II complex. We have found many synthetic genetic interactions between factors within the Paf1p-Cdc73p complex, including the lethality of paf1Delta ccr4Delta, paf1Delta hpr1Delta, ccr4Delta hpr1Delta, and ccr4Delta gal11Delta double mutants. In addition, paf1Delta and ccr4Delta are lethal in combination with srb5Delta, indicating that the factors within and between the two RNA polymerase II complexes have overlapping essential functions. We have used differential display to identify several genes whose expression is affected by mutations in components of the Paf1p-Cdc73p-Pol II complex. Additionally, as previously observed for hpr1Delta, deleting PAF1 or CDC73 leads to elevated recombination between direct repeats. The paf1Delta and ccr4Delta mutations, as well as gal11Delta, demonstrate sensitivity to cell wall-damaging agents, rescue of the temperature-sensitive phenotype by sorbitol, and reduced expression of genes involved in cell wall biosynthesis. This unusual combination of effects on recombination and cell wall integrity has also been observed for mutations in genes in the Pkc1p-Mpk1p kinase cascade. Consistent with a role for this novel form of RNA polymerase II in the Pkc1p-Mpk1p signaling pathway, we find that paf1Delta mpk1Delta and paf1Delta pkc1Delta double mutants do not demonstrate an enhanced phenotype relative to the single mutants. Our observation that the Mpk1p kinase is fully active in a paf1Delta strain indicates that the Paf1p-Cdc73p complex may function downstream of the Pkc1p-Mpk1p cascade to regulate the expression of a subset of yeast genes.
酵母含有至少两种复杂形式的RNA聚合酶II（Pol II），一种包含Srb蛋白，另一种在生化性质上不同，其特征是存在Paf1p和Cdc73p（X. Shi等人，《分子与细胞生物学》17:1160 - 1169，1997）。在这项工作中，我们证明Ccr4p和Hpr1p是Paf1p - Cdc73p - Pol II复合物的组成成分。我们发现Paf1p - Cdc73p复合物中的因子之间存在许多合成遗传相互作用，包括paf1Δccr4Δ、paf1Δhpr1Δ、ccr4Δhpr1Δ和ccr4Δgal11Δ双突变体的致死性。此外，paf1Δ和ccr4Δ与srb5Δ组合是致死的，这表明两种RNA聚合酶II复合物内部和之间的因子具有重叠的基本功能。我们使用差异显示来鉴定几个基因，其表达受Paf1p - Cdc73p - Pol II复合物成分突变的影响。另外，如先前对hpr1Δ所观察到的，缺失PAF1或CDC73会导致直接重复序列之间的重组增加。paf1Δ和ccr4Δ突变以及gal11Δ，表现出对细胞壁损伤剂的敏感性，山梨醇可挽救温度敏感型表型，并且参与细胞壁生物合成的基因表达降低。在Pkc1p - Mpk1p激酶级联反应中的基因突变也观察到了这种对重组和细胞壁完整性的异常综合影响。与这种新型RNA聚合酶II在Pkc1p - Mpk1p信号通路中的作用一致，我们发现paf1Δmpk1Δ和paf1Δpkc1Δ双突变体相对于单突变体没有表现出增强的表型。我们观察到Mpk1p激酶在paf1Δ菌株中完全活跃，这表明Paf1p - Cdc73p复合物可能在Pkc1p - Mpk1p级联反应的下游起作用，以调节酵母基因子集的表达。
