Smith-Kinnaman Whitney R, Berna Michael J, Hunter Gerald O, True Jason D, Hsu Peter, Cabello Gabriela I, Fox Melanie J, Varani Gabriele, Mosley Amber L
Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
Mol Biosyst. 2014 Jul;10(7):1730-41. doi: 10.1039/c4mb00109e.
The phosphatase Rtr1 has been implicated in dephosphorylation of the RNA Polymerase II (RNAPII) C-terminal domain (CTD) during transcription elongation and in regulation of nuclear import of RNAPII. Although it has been shown that Rtr1 interacts with RNAPII in yeast and humans, the specific mechanisms that underlie Rtr1 recruitment to RNAPII have not been elucidated. To address this, we have performed an in-depth proteomic analysis of Rtr1 interacting proteins in yeast. Our studies revealed that hyperphosphorylated RNAPII is the primary interacting partner for Rtr1. To extend these findings, we performed quantitative proteomic analyses of Rtr1 interactions in yeast strains deleted for CTK1, the gene encoding the catalytic subunit of the CTD kinase I (CTDK-I) complex. Interestingly, we found that the interaction between Rtr1 and RNAPII is decreased in ctk1Δ strains. We hypothesize that serine-2 CTD phosphorylation is required for Rtr1 recruitment to RNAPII during transcription elongation.
磷酸酶Rtr1在转录延伸过程中参与RNA聚合酶II（RNAPII）羧基末端结构域（CTD）的去磷酸化，并参与RNAPII的核输入调控。尽管已表明Rtr1在酵母和人类中与RNAPII相互作用，但Rtr1被招募至RNAPII的具体机制尚未阐明。为解决这一问题，我们对酵母中与Rtr1相互作用的蛋白质进行了深入的蛋白质组学分析。我们的研究表明，高度磷酸化的RNAPII是Rtr1的主要相互作用伴侣。为扩展这些发现，我们对缺失CTK1（编码CTD激酶I（CTDK-I）复合体催化亚基的基因）的酵母菌株中Rtr1的相互作用进行了定量蛋白质组学分析。有趣的是，我们发现ctk1Δ菌株中Rtr1与RNAPII之间的相互作用减弱。我们推测，在转录延伸过程中，CTD丝氨酸2位点的磷酸化是Rtr1被招募至RNAPII所必需的。
