Identification of a small TAF complex and its role in the assembly of TAF-containing complexes

• Published in: PloS one 2007-03, Vol.2 (3), p.e316
• Main Authors: Demény, Màté A, Soutoglou, Evi, Nagy, Zita, Scheer, Elisabeth, Jànoshàzi, Agnes, Richardot, Magalie, Argentini, Manuela, Kessler, Pascal, Tora, Laszlo
• Format: Article
• Language: English
• Subjects: Acids; Amino Acid Sequence; Animals; Assembly; Biochemistry, Molecular Biology; Blotting, Western; Complex formation; DNA, Complementary - genetics; DNA-directed RNA polymerase; Drosophila; Fungal Proteins - chemistry; Fungal Proteins - genetics; Fungal Proteins - metabolism; Gene Amplification; Gene expression; Gene regulation; Humans; Insects; Life Sciences; Ligands; Mass spectrometry; Mice; Molecular Biology; Molecular Biology/Transcription Initiation and Activation; Nuclei; Polymerase; Polymerase Chain Reaction - methods; Proline; Protein binding; Protein Subunits - chemistry; Proteins; Proteomics; Ribonucleic acid; RNA; RNA polymerase; RNA polymerase II; Scientific imaging; Tata box; TATA Box Binding Protein-Like Proteins - chemistry; TATA Box Binding Protein-Like Proteins - genetics; TATA Box Binding Protein-Like Proteins - metabolism; TATA-Binding Protein Associated Factors - chemistry; TATA-Binding Protein Associated Factors - genetics; TFIID protein; Transcription; Transcription factors; Transcription Factors - chemistry; Transcription Factors - genetics; Transfection; Yeasts - genetics
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0000316

TFIID plays a role in nucleating RNA polymerase II preinitiation complex assembly on protein-coding genes. TFIID is a multisubunit complex comprised of the TATA box binding protein (TBP) and 14 TBP-associated factors (TAFs). Another class of multiprotein transcriptional regulatory complexes having histone acetyl transferase (HAT) activity, and containing TAFs, includes TFTC, STAGA and the PCAF/GCN5 complex. Looking for as yet undiscovered subunits by a proteomic approach, we had identified TAF8 and SPT7L in human TFTC preparations. Subsequently, however, we demonstrated that TAF8 was not a stable component of TFTC, but that it is present in a small TAF complex (SMAT), containing TAF8, TAF10 and SPT7L, that co-purified with TFTC. Thus, TAF8 is a subunit of both TFIID and SMAT. The latter has to be involved in a pathway of complex formation distinct from the other known TAF complexes, since these three histone fold (HF)-containing proteins (TAF8, TAF10 and SPT7L) can never be found together either in TFIID or in STAGA/TFTC HAT complexes. Here we show that TAF8 is absolutely necessary for the integration of TAF10 in a higher order TFIID core complex containing seven TAFs. TAF8 forms a heterodimer with TAF10 through its HF and proline rich domains, and also interacts with SPT7L through its C-terminal region, and the three proteins form a complex in vitro and in vivo. Thus, the TAF8-TAF10 and TAF10-SPT7L HF pairs, and also the SMAT complex, seem to be important regulators of the composition of different TFIID and/or STAGA/TFTC complexes in the nucleus and consequently may play a role in gene regulation.