Identification of TATA-binding protein-free TAF(II)-containing complex subunits suggests a role in nucleosome acetylation and signal transduction

Recently we identified a novel human (h) multiprotein complex, called TATA- binding protein (TBP)-free TAF(II)containing complex (TFTC), which is able to nucleate RNA polymerase II transcription and can mediate transcriptional activation. Here we demonstrate that TFTC, similar to other TBP-free TAF(I I), complexes (yeast SAGA, hSTAGA, and hPCAF) contains the acetyltransferas e hGCN5 and is able to acetylate histones in both a free and a nucleosomal context. The recently described TRRAP cofactor for oncogenic transcription factor pathways was also characterized as a TFTC subunit, Furthermore, we i dentified four other previously uncharacterized subunits of TFTC: hADA3, hT AF(II)150, hSPT3, and hPAF65 beta. Thus, the polypeptide composition of TFT C suggests that TFTC is recruited to chromatin templates by activators to a cetylate histones and thus may potentiate initiation and activation of tran scription.