RECONSTITUTION OF HUMAN TFIIA ACTIVITY FROM RECOMBINANT POLYPEPTIDES - A ROLE IN TFIID-MEDIATED TRANSCRIPTION

Human TFIIA activity is composed of three subunits (alpha, beta, gamma ). Here we report the isolation of a human cDNA clone encoding the gam ma-subunit and the reconstitution of TFIIA activity from recombinant p olypeptides (holo-TFIIA). Protein-protein interaction analysis establi shed that the beta and gamma subunits of TFIIA interact with the TBP c omponent of TFIID. The alpha-subunit is recruited into the complex by association with the gamma-subunit. functional studies indicate that r ecombinant TFIIA stimulates basal TFIID-dependent transcription but is without effect on TBP-dependent transcription. Our studies indicate t hat TEIIA not only functions by physically removing negative component s present in TFIID (antirepression), as demonstrated previously, but t hat it can stimulate basal transcription through components of the TFI ID complex. Holo-TFIIA also stimulated activation of transcription in vitro as well as in vivo in transfected HeLa cells.