Mediator head module structure and functional interactions.
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.
Department of Cell Biology, The Scripps Research Institute, La Jolla, California, USA.
Gang
G
Cai
Tsuyoshi
T
Imasaki
Kentaro
K
Yamada
Francesco
F
Cardelli
Yuichiro
Y
Takagi
Francisco J
FJ
Asturias
D056892:Mediator Complex / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D008958:Models, Molecular; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012319:RNA Polymerase II / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D013329:Structure-Activity Relationship; D014158:Transcription, Genetic
D056892:Mediator Complex; D029701:Saccharomyces cerevisiae Proteins; D012319:RNA Polymerase II; C423309:RPB4 protein, S cerevisiae; C470553:RPB7 protein, S cerevisiae