SCIENCE AT THE EDGE SEMINAR

Friday, 18 February 2011 at 11:30am

Room 1400 Biomedical and Physical Sciences Bldg.

Refreshments at 11:15


Speaker: Joan Conaway
         Stowers Institute for Medical Research
         Kansas City, MO

Title:   The Mediator of RNA Polymerase II Transcription: Links to
         Transcription Elongation and Leukemogenesis


Abstract:

Promoter proximal pausing by initiated RNA polymerase II (Pol II) and regulated
release of paused polymerase into productive elongation has emerged as a major
mechanism of transcription activation. Reactivation of paused Pol II has been
shown to correlate with recruitment of a so-called Super-Elongation Complex or
SEC that contains the transcription elongation factors ELL/EAF and P-TEFb, as
well as a collection of additional proteins encoded by genes involved in
translocations with the MLL gene in leukemia.  Our lab has recently obtained
evidence for a role of human Mediator in recruiting SEC and another
ELL/EAF-containing complex to genes.  I will present evidence that a conserved
N-terminal domain in the Mediator subunit Med26 provides docking sites for
ELL/EAF, P-TEFb, and associated proteins as well as the general initiation
factor TFIID.  In addition, I will present evidence consistent with the model
that Med26 may function as a molecular switch that interacts first with the
Pol II initiation complex through direct interactions with TFIID and then
"exchanges" TFIID for complexes containing elongation factors ELL/EAF and
P-TEFb to facilitate the transition of Pol II into the elongation stage of
transcription.