We report genome-wide analyses that establish Maf1 as a general and direct repressor of yeast RNA polymerase (Pol) III transcription. Chromatin immunoprecipitation (ChIP) coupled to microarray hybridization experiments showed an increased association of Maf1 to Pol III-transcribed genes under repressing condition (rapamycin treatment) correlated with a dissociation of Brf1 and Pol III. Maf1 can exist in various phosphorylation states and interacts with Pol III in a dephosphorylated state. The largest subunit of Pol III, C160, was identified as a target of Maf1. Under repressing conditions, Maf1 is dephosphorylated and accumulates in the nucleus, and Pol III-Maf1 interaction increases. Mutations in protein phosphatase type 2A (PP2A) catalytic subunit-encoding genes prevented rapamycin-induced Maf1 dephosphorylation, its nuclear accumulation, and repression of Pol III transcription. The results indicate that Pol III transcription can be globally and rapidly downregulated via dephosphorylation and relocation of a general negative cofactor.

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Journal Article | Research Support, Non-U.S. Gov't

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Oficjalska-Pham D, Harismendy O, Smagowicz WJ, Gonzalez de Peredo A, Boguta M, Sentenac A, Lefebvre O

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