Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland.
Trends Biochem Sci. 2011 Sep;36(9):451-6. doi: 10.1016/j.tibs.2011.06.008. Epub 2011 Aug 2.
The synthesis of tRNA by yeast RNA polymerase III (Pol III) is regulated in response to changing environmental conditions. This control is mediated by Maf1, the global negative regulator of Pol III transcription conserved from yeast to humans. Details regarding the molecular basis of Pol III repression by Maf1 are now emerging from recently reported structural and biochemical data on Pol III and Maf1. Efficient Pol III transcription, following the shift of cells from a non-fermentable carbon source to glucose, requires phosphorylation of Maf1. One of the newly identified Maf1 kinases is the chromatin-bound casein kinase II (CK2). Current studies have allowed us to propose an innovative mechanism of Pol III regulation. We suggest that CK2-mediated phosphorylation of Maf1, occurring directly on tDNA chromatin, controls Pol III recycling.
酵母 RNA 聚合酶 III（Pol III）合成 tRNA 的过程受到环境条件变化的调控。这种调控是通过 Maf1 介导的，Maf1 是从酵母到人类都保守的 Pol III 转录的全局负调控因子。最近关于 Pol III 和 Maf1 的结构和生化数据的报告，揭示了 Maf1 对 Pol III 抑制的分子基础的详细信息。当细胞从非发酵碳源转变为葡萄糖时，Maf1 的磷酸化对于高效的 Pol III 转录是必需的。新鉴定的 Maf1 激酶之一是结合在染色质上的酪蛋白激酶 II（CK2）。目前的研究使我们能够提出 Pol III 调控的一个创新机制。我们提出，CK2 介导的 Maf1 在 tDNA 染色质上的直接磷酸化，控制着 Pol III 的循环利用。
