Mediator head module structure and functional interactions.

Nat Struct Mol Biol 2010 Mar 14;17(3):273-9. Epub 2010 Feb 14.

Department of Cell Biology, The Scripps Research Institute, La Jolla, California, USA.

We used single-particle electron microscopy to characterize the structure and subunit organization of the Mediator Head module that controls Mediator-RNA polymerase II (RNAPII) and Mediator-promoter interactions. The Head module adopts several conformations differing in the position of a movable jaw formed by the Med18-Med20 subcomplex. We also characterized, by structural, biochemical and genetic means, the interactions of the Head module with TATA-binding protein (TBP) and RNAPII subunits Rpb4 and Rpb7. TBP binds near the Med18-Med20 attachment point and stabilizes an open conformation of the Head module. Rpb4 and Rpb7 bind between the Head jaws, establishing contacts essential for yeast-cell viability. These results, and consideration of the structure of the Mediator-RNAPII holoenzyme, shed light on the stabilization of the pre-initiation complex by Mediator and suggest how Mediator might influence initiation by modulating polymerase conformation and interaction with promoter DNA.

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http://dx.doi.org/10.1038/nsmb.1757DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2925518PMC
March 2010
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