Identification of a small TAF complex and its role in the assembly of TAF-containing complexes.
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.
Demény
Màté A
MA
Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique UMR 7104, Institut National de la Santé et de la Recherche Médicale U 596, Université Louis Pasteur de Strasbourg, Illkirch, Strasbourg, France.
Soutoglou
Evi
E
Nagy
Zita
Z
Scheer
Elisabeth
E
Jànoshàzi
Agnes
A
Richardot
Magalie
M
Argentini
Manuela
M
Kessler
Pascal
P
Tora
Laszlo
L
D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D018076:DNA, Complementary / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005784:Gene Amplification; D006801:Humans; D051379:Mice; D016133:Polymerase Chain Reaction / Q000379:methods; D021122:Protein Subunits / Q000737:chemistry; D035182:TATA Box Binding Protein-Like Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D035381:TATA-Binding Protein Associated Factors / Q000737:chemistry / Q000235:genetics*; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics; D014162:Transfection; D015003:Yeasts / Q000235:genetics
D018076:DNA, Complementary; D005656:Fungal Proteins; D021122:Protein Subunits; C501078:SUPT7L protein, human; D035182:TATA Box Binding Protein-Like Proteins; D035381:TATA-Binding Protein Associated Factors; D014157:Transcription Factors