Bud27 is a prefoldin-like protein that participates in transcriptional regulation mediated by the three RNA polymerases in Saccharomyces cerevisiae. Lack of Bud27 significantly affects RNA pol III transcription, although the involved mechanisms have not been characterized. Here, we show that Bud27 regulates the phosphorylation state of the RNA pol III transcriptional repressor, Maf1, influences its nuclear localization, and likely its activity. We demonstrate that Bud27 is associated with the Maf1 main phosphatase PP4 in vivo, and that this interaction is required for proper Maf1 dephosphorylation. Lack of Bud27 decreases the interaction among PP4 and Maf1, Maf1 dephosphorylation, and its nuclear entry. Our data uncover a new nuclear function of Bud27, identify PP4 as a novel Bud27 interactor and demonstrate the effect of this prefoldin-like protein on the posttranslational regulation of Maf1. Finally, our data reveal a broader effect of Bud27 on PP4 activity by influencing, at least, the phosphorylation of Rad53.

中文翻译：

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在酿酒酵母中，Maf1 磷酸化是通过类前折叠蛋白 Bud27 对 PP4 磷酸酶的作用来调节的


Bud27 是一种前折叠蛋白样蛋白，参与酿酒酵母中三种 RNA 聚合酶介导的转录调节。 Bud27 的缺失会显着影响 RNA pol III 的转录，但所涉及的机制尚未得到表征。在这里，我们表明 Bud27 调节 RNA pol III 转录阻遏蛋白 Maf1 的磷酸化状态，影响其核定位，并可能影响其活性。我们证明 Bud27 在体内与 Maf1 主要磷酸酶 PP4 相关，并且这种相互作用是 Maf1 正确去磷酸化所必需的。 Bud27 的缺乏会降低 PP4 和 Maf1 之间的相互作用、Maf1 去磷酸化及其入核。我们的数据揭示了 Bud27 的新核功能，将 PP4 鉴定为新型 Bud27 相互作用蛋白，并证明了这种前折叠蛋白样蛋白对 Maf1 翻译后调节的影响。最后，我们的数据揭示了 Bud27 至少通过影响 Rad53 的磷酸化对 PP4 活性产生更广泛的影响。