Reconstitution of transcription factor SL1: exclusive binding of TBP by SL1 or TFIID subunits.
RNA polymerase I and II transcription factors SL1 and TFIID, respectively, are composed of the TATA-binding protein (TBP) and a set of TBP-associated factors (TAFs) responsible for promoter recognition. How the universal transcription factor TBP becomes committed to a TFIID or SL1 complex has not been known. Complementary DNAs encoding each of the three TAFIs that are integral components of SL1 have not been isolated. Analysis of subunit interactions indicated that the three TAFIs can bind individually and specifically to TBP. In addition, these TAFIs interact with each other to form a stable TBP-TAF complex. When TBP was bound first by either TAFI110, 63, or 48, subunits of TFIID such as TAFII250 and 150 did not bind TBP. Conversely, if TBP first formed a complex with TAFII250 or 150, the subunits of SL1 did not bind TBP. These results suggest that a mutually exclusive binding specificity for TBP intrinsic to SL1 and TFIID subunits directs the formation of promoter- and RNA polymerase-selective TBP-TAF complexes.
Comai
L
L
Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California at Berkeley 94720-3204.
Zomerdijk
J C
JC
Beckmann
H
H
Zhou
S
S
Admon
A
A
Tjian
R
R
D000595:Amino Acid Sequence; D001483:Base Sequence; D001667:Binding, Competitive; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D035463:Pol1 Transcription Initiation Complex Proteins; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012318:RNA Polymerase I / Q000378:metabolism; D016385:TATA Box; D035381:TATA-Binding Protein Associated Factors; D035181:TATA-Box Binding Protein; D035362:Transcription Factor TFIID; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014158:Transcription, Genetic
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D035463:Pol1 Transcription Initiation Complex Proteins; C091131:TAF1A protein, human; C091129:TAF1B protein, human; C486319:TAF1C protein, human; D035381:TATA-Binding Protein Associated Factors; D035181:TATA-Box Binding Protein; D035362:Transcription Factor TFIID; D014157:Transcription Factors; C063660:transcription initiation factor TIF-IB; D012318:RNA Polymerase I