TAF25p, a non-histone-like subunit of TFIID and SAGA complexes, is essential for total mRNA gene transcription in vivo

We demonstrate, utilizing a temperature conditional mutant allele of the ge ne encoding TAF25p, that this non-histone-like TBP-associated factor, which is shared between the TFIID and SAGA complexes, is required for hulk mRNA gene transcription by RNA polymerase II in vivo. Immunoblotting experiments indicate that at the restrictive temperature, inactivation of TAF25p funct ion results in a reduction of the levels of numerous TFIID and SAGA subunit s, indicating its loss of function, like the histone-like TAFs, causes degr adation of the constituents of these two multisubunit complexes. These data suggest that TAF25p plays a key structural role in maintaining TFIID and S AGA complex integrity, This is the first demonstration that a non-histone-l ike TAF is required for continuous, high level RNA polymerase II-mediated m RNA gene transcription in living yeast cells.