Molecular Architecture of the Basal Transcription Factor B-TFIID

• Published in: The Journal of biological chemistry Vol. 279; no. 21; pp. 21802 - 21807
• Main Authors: Pereira, Lloyd A, Klejman, Marcin P, Ruhlmann, Christine, Kavelaars, François, Oulad-Abdelghani, Mustapha, Timmers, H Th Marc, Schultz, Patrick
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 21-05-2004
• Subjects: Adenosine Triphosphate - chemistry; Biochemistry, Molecular Biology; HeLa Cells; Humans; Life Sciences; Microscopy, Electron; Microscopy, Immunoelectron; Protein Binding; Protein Conformation; Protein Structure, Tertiary; Recombinant Proteins - chemistry; RNA Polymerase II - chemistry; TATA-Binding Protein Associated Factors - chemistry; TATA-Binding Protein Associated Factors - genetics; TATA-Box Binding Protein - chemistry; Transcription Factor TFIID - chemistry; Transcription Factor TFIID - genetics; Transcription, Genetic
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M313519200

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 Å. B-TFIID is 15 × 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.