Journal
MOLECULAR AND CELLULAR BIOLOGY
Volume 23, Issue 1, Pages 349-358Publisher
AMER SOC MICROBIOLOGY
DOI: 10.1128/MCB.23.1.349-358.2003
Keywords
-
Categories
Funding
- NATIONAL INSTITUTE OF GENERAL MEDICAL SCIENCES [R01GM053451] Funding Source: NIH RePORTER
- NIGMS NIH HHS [GM53451, R01 GM053451] Funding Source: Medline
Ask authors/readers for more resources
RNA polymerase II (Pol II) Mediator plays an essential role in both basal and activated transcription. Previously, subunits of the Sin4 Mediator complex (Sin4, Pgd1, Gal11, and Med2) have been implicated in both positive and negative transcriptional regulation. Furthermore, it was proposed that this subcomplex constitutes an activator-binding domain. A yeast nuclear-extract system was used to investigate the biochemical role of the Sin4 complex. In contrast to previous findings, we found at least two general activator-independent roles for the Sin4 complex. First, mutations in sin4 and pgd1 destabilized the Pol II-Med complex, leading to a reduced rate and extent of preinitiation complex (PIC) formation both in the presence and absence of activators. Although reduced in amount compared with the wild type, PICs that are formed lacking the Sin4 complex are stable and can initiate transcription normally. Second, mutation of pgd1 causes partial disruption of the Sin4 complex and leads to a defect in transcription reinitiation. This defect is caused by dissociation of mutant Mediator from promoters after initiation, leading to nonfunctional Scaffold complexes. These results show that function of the Sin4 complex is not essential for transcription activation in a crude in vitro system but that it plays key roles in the general transcription mechanism.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available