Proteomics reveals a physical and functional link between hepatocyte nuclear factor 4alpha and transcription factor IID.
Proteomic analyses have contributed substantially to our understanding of diverse cellular processes. Improvements in the sensitivity of mass spectrometry approaches are enabling more in-depth analyses of protein-protein networks and, in some cases, are providing surprising new insights into well established, longstanding problems. Here, we describe such a proteomic analysis that exploits MudPIT mass spectrometry and has led to the discovery of a physical and functional link between the orphan nuclear receptor hepatocyte nuclear factor 4alpha (HNF4alpha) and transcription factor IID (TFIID). A systematic characterization of the HNF4alpha-TFIID link revealed that the HNF4alpha DNA-binding domain binds directly to the TATA box-binding protein (TBP) and, through this interaction, can target TBP or TFIID to promoters containing HNF4alpha-binding sites in vitro. Supporting the functional significance of this interaction, an HNF4alpha mutation that blocks binding of TBP to HNF4alpha interferes with HNF4alpha transactivation activity in cells. These findings identify an unexpected role for the HNF4alpha DNA-binding domain in mediating key regulatory interactions and provide new insights into the roles of HNF4alpha and TFIID in RNA polymerase II transcription.
Takahashi
Hidehisa
H
Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA.
Martin-Brown
Skylar
S
Washburn
Michael P
MP
Florens
Laurence
L
Conaway
Joan W
JW
Conaway
Ronald C
RC
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D006367:HeLa Cells; D051557:Hepatocyte Nuclear Factor 4 / Q000378:metabolism*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D040901:Proteomics / Q000379:methods*; D035362:Transcription Factor TFIID / Q000378:metabolism*
D051557:Hepatocyte Nuclear Factor 4; D035362:Transcription Factor TFIID