Isoform-specific interaction of HP1 with human TAFII130

AUTOR(ES)

Vassallo, Milo F.

FONTE

The National Academy of Sciences

RESUMO

The general transcription factor TFIID facilitates recruitment of the transcription machinery to gene promoters and regulates initiation of transcription by RNA polymerase II. hTAFII130, a component of TFIID, interacts with and serves as a coactivator for multiple transcriptional regulatory proteins, including Sp1 and CREB. A yeast two-hybrid screen has identified an interaction between hTAFII130 and heterochromatin protein 1 (HP1), a chromatin-associated protein whose function has been implicated in gene silencing. We find that hTAFII130 associates with HP1 in an isoform-specific manner: HP1α and HP1γ bind to hTAFII130, but not HP1β. In addition, we show that endogenous hTAFII130 and components of TFIID in HeLa nuclear extracts associate with glutathione S-transferase-HP1α and -HP1γ. hTAFII130 possesses a pentapeptide HP1-binding motif, and mutation of the hTAFII130 HP1 box compromises the interaction of hTAFII130 with HP1. We demonstrate that Gal4-HP1 proteins interfere with hTAFII130-mediated activation of transcription. Our results suggest that HP1α and HP1γ associate with hTAFII130 to mediate repression of transcription, supporting a new model of transcriptional repression involving a specific interaction between a component of TFIID and chromatin.

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