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Published on: December 29, 2023
Mediator complex association with constitutively transcribed genes in yeast
Suraiya A Ansari1, Qiye He, Randall H Morse
1Laboratory of Molecular Genetics, Wadsworth Center, New York State Department of Health, Albany, NY 12201-2002, USA.
Summary
Mediator complex is crucial for RNA Pol II transcription in yeast. Its association with constitutively transcribed genes is direct and activator-dependent, functioning as a general transcription factor.
Area of Science:
- Molecular Biology
- Yeast Genetics
- Gene Transcription
Background:
- Mediator is a large complex essential for eukaryotic mRNA transcription by RNA Polymerase II.
- Recent studies suggest Mediator's role in transcriptional activation is activator-dependent and potentially indirect for some genes.
Purpose of the Study:
- Investigate Mediator association with constitutively transcribed genes in yeast.
- Determine the directness of Mediator's requirement for RNA Polymerase II association.
Main Methods:
- Utilized a yeast strain with a temperature-sensitive mutation in the Mediator subunit Srb4.
- Compared Mediator association in mutant and wild-type yeast strains at various gene promoters.
- Analyzed Mediator module dissociation and RNA Polymerase II association.
Main Results:
- Mediator shows modest association with constitutively active genes, significantly reduced in srb4 mutant yeast.
- Mediator's tail module remains associated with ribosomal protein gene promoters, while head/middle modules are lost.
- Rap1 is required for Mediator recruitment via the tail module at Rap1-dependent promoters.
- RNA Polymerase II association is severely affected in srb4 mutant yeast.
Conclusions:
- Mediator is directly required for RNA Polymerase II association at constitutively transcribed genes.
- Findings support Mediator functioning as a general transcription factor in yeast.
- Mediator recruitment is at least partially dependent on specific transcription factors like Rap1.
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