Evidence That Mediator is Essential for Pol II Transcription, but is Not a Required Component of the Preinitiation Complex in Vivo

Overview

Journal Elife

Specialty Biology

Date 2017 Jul 13

PMID 28699889

Citations 29

Authors

Natalia Petrenko

Yi Jin

Koon Ho Wong

Kevin Struhl

Affiliations

Soon will be listed here.

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 strong evidence that Mediator is essential for Pol II transcription and stimulates PIC formation, but it is not a required component of the PIC in vivo.

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