A role for the Pcl9‐Pho85 cyclin–cdk complex at the M/G1 boundary in Saccharomyces cerevisiae
A role for the Pcl9‐Pho85 cyclin–cdk complex at the M/G1 boundary in Saccharomyces cerevisiae
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DOI：
10.1046/j.1365-2958.1998.00773.x
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发表时间：
1998-04
影响因子：
3.6
通讯作者：
C. Tennyson;Jinhwa Lee;B. Andrews
中科院分区：
文献类型：
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作者：
C. Tennyson;Jinhwa Lee;B. Andrews
PHO 85是一种细胞周期蛋白依赖性激酶（CDK），在磷酸盐和糖原代谢以及细胞周期进程中发挥作用。作为CDK，Pho 85通过与Pho 85细胞周期蛋白（Pcls）结合而被激活，其中已知10种。PCL 1、PCL 2和PCL 9是Pho 85细胞周期蛋白家族中唯一以细胞周期调控模式表达的成员。我们发现，PCL 9在细胞周期的晚期M/早期G1期表达，并被转录因子Swi 5激活。这种调控模式与PCL 1和PCL 2不同，后者在G1期表达较晚，主要由转录因子SBF调控。使用体外翻译蛋白的免疫共沉淀实验表明，Pcl 9和Pho 85形成复合物。此外，从酵母裂解物免疫沉淀的Pcl 9复合物能够磷酸化的外源性底物Pho 4。Pcl 9相关激酶活性依赖于PHO 85，表明Pcl 9和PHO 85在体内形成功能活性激酶复合物。在二倍体细胞中缺失PCL 9导致18%的细胞随机而非双极出芽。与此相反，PCL 9的近亲PCL 2的缺失对出芽模式没有影响。删除更多的PCL 1，2亚家族成员（包括PCL 9）增加了细胞群中随机出芽的百分比。当删除PCL 1，2亚家族的所有成员时，73%的细胞随机发芽，该值与删除CDK伴侣PHO 85时获得的值相似。我们的研究结果表明，PCL 9和PHO 85形成一个功能激酶复合物，并建议在M/G1边界的PHO 85 CDKs的作用。
PHO85 is a cyclin‐dependent kinase (CDK) with roles in phosphate and glycogen metabolism and cell cycle progression. As a CDK, Pho85 is activated by association with Pho85 cyclins (Pcls), of which 10 are known. PCL1, PCL2 and PCL9 are the only members of the Pho85 cyclin family that are expressed in a cell cycle‐regulated pattern. We found that PCL9 is expressed in late M/early G1 phase of the cell cycle and is activated by the transcription factor, Swi5. This pattern of regulation is different from PCL1 and PCL2, which are expressed later in G1 phase and are regulated primarily by the transcription factor SBF. Co‐immunoprecipitation experiments using in vitro translated proteins showed that Pcl9 and Pho85 form a complex. Furthermore, immunoprecipitated Pcl9 complexes from yeast lysates were capable of phosphorylating the exogenous substrate Pho4. The Pcl9‐associated kinase activity was dependent on PHO85, showing that Pcl9 and Pho85 form a functionally active kinase complex in vivo. Deletion of PCL9 in diploid cells caused random, rather than bipolar, budding in 18% of cells. In contrast, deletion of PCL2, the closest relative of PCL9, had no effect on the budding pattern. Deleting more members of the PCL1,2 subfamily (which includes PCL9 ) increased the percentage of random budding in the cell population. When all members of the PCL1,2 subfamily were deleted, 73% of cells budded randomly, a value similar to that obtained when the CDK partner PHO85 was deleted. Our results show that PCL9 and PHO85 form a functional kinase complex and suggest a role for Pho85 CDKs at the M/G1 boundary.