Genomics

Dataset Information

155

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


ABSTRACT: Mediator, a transcriptional co-activator complex, is recruited to enhancers by DNA-binding activators via its tail module, and it interacts with RNA polymerase (Pol) II as part of the preinitiation complex (PIC) via its head module. Although Mediator has been described as a general transcription factor, it is unclear if it is essential for Pol II transcription and/or is a required component of the PIC in vivo. We comprehensively analyze this issue by measuring Pol II transcription upon rapid depletion of individual or multiple Mediator subunits from the nucleus. Depletion of individual subunits, even those essential for cell growth, causes a general but only modest decrease in Pol II transcription. Transcriptional effects are stronger on SAGA-dependent genes as opposed to TFIID-dependent genes. Thus, Mediator modules that associate either with the enhancer or with the core promoter confer partial transcriptional activity. Furthermore, Pol II transcription can occur when Mediator is not detected at core promoters. In contrast, simultaneous depletion of all Mediator modules causes a drastic decrease in Pol II transcription that is roughly comparable to the effect observed upon anchor-away-mediated depletion of Pol II or TBP. These results provide strong evidence that Mediator is essential for Pol II transcription in vivo, but that it is not a required component of the PIC. Overall design: Chip-seq performed with 8WG14 antibodies before and after the anchor-away of 7 Mediator subunits, as well as in a WT strain, in a TBP anchor-away strain, an Rpb-1 anchor-away strain, and in the "Triple" mutant, where the Mediator tail is deleted and Med17 is anchored away.

INSTRUMENT(S): Illumina MiSeq (Saccharomyces cerevisiae)

SUBMITTER: Natalia Petrenko 

PROVIDER: GSE93190 | GEO | 2017-07-13

SECONDARY ACCESSION(S): PRJNA360382

REPOSITORIES: GEO

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Publications

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

Petrenko Natalia N   Jin Yi Y   Wong Koon Ho KH   Struhl Kevin K  

eLife 20170712


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 subun  ...[more]

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