Molecular architecture of the basal transcription factor B-TFIID.
BTAF1 (formerly named TAF(II)170/TAF-172) is an essential, evolutionarily conserved member of the SNF2-like family of ATPase proteins and together with TATA-binding protein (TBP) forms the B-TFIID complex. BTAF1 has been proposed to play a key role in the dynamic regulation of TBP function in RNA polymerase II transcription. We have determined the structure of native B-TFIID purified from human cells by electron microscopy and by image analysis of single particles at a resolution of 28 A. B-TFIID is 15 x 9 nm in size and is organized into a large domain of about 170 kDa, which can be subdivided into two domains. Extending from this domain is a long thumb, which in turn is divided into subdomains of about 25, 15, and 35 kDa, the largest of which is located at the end of the thumb. Immunolabeling experiments localize the extreme carboxyl terminus of BTAF1 within the 170-kDa domain, whereas the amino terminus and TBP co-localize to the end of the protruding thumb. The central portion of BTAF1 localizes to the base of the thumb. Comparison of the native B-TFIID with its recombinant form shows that both share a similar domain organization. Collectively, these data provide the first structural model of the B-TFIID complex and map its key functional domains.
Department of Physiological Chemistry, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands.
Lloyd A
LA
Pereira
Marcin P
MP
Klejman
Christine
C
Ruhlmann
François
F
Kavelaars
Mustapha
M
Oulad-Abdelghani
H Th Marc
HT
Timmers
Patrick
P
Schultz
D000255:Adenosine Triphosphate / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D008854:Microscopy, Electron; D016253:Microscopy, Immunoelectron; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012319:RNA Polymerase II / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry; D035381:TATA-Binding Protein Associated Factors / Q000737:chemistry* / Q000235:genetics; D035181:TATA-Box Binding Protein / Q000737:chemistry*; D035362:Transcription Factor TFIID / Q000737:chemistry* / Q000235:genetics; D014158:Transcription, Genetic
C109035:BTAF1 protein, human; D011994:Recombinant Proteins; D035381:TATA-Binding Protein Associated Factors; D035181:TATA-Box Binding Protein; D035362:Transcription Factor TFIID; D000255:Adenosine Triphosphate; D012319:RNA Polymerase II