Evidence that Mediator is essential for Pol II transcription, but is not a required component of the preinitiation complex in vivo.

ABSTRACT: The Mediator complex has been described as a general transcription factor, but it is unclear if it is essential for Pol II transcription and/or is a required component of the preinitiation complex (PIC) in vivo. Here, we show that depletion of individual subunits, even those essential for cell growth, causes a general but only modest decrease in transcription. In contrast, simultaneous depletion of all Mediator modules causes a drastic decrease in transcription. Depletion of head or middle subunits, but not tail subunits, causes a downstream shift in the Pol II occupancy profile, suggesting that Mediator at the core promoter inhibits promoter escape. Interestingly, a functional PIC and Pol II transcription can occur when Mediator is not detected at core promoters. These results provide str

SUBMITTER: Petrenko N 

PROVIDER: S-EPMC5529107 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature