Molecular genetic dissection of TAF25, an essential yeast gene encoding a subunit shared by TFIID and SAGA multiprotein transcription factors

We have performed a systematic structure-function analysis of Saccharomyces cerevisiae TAF25, an evolutionarily conserved, single-copy essential gene which encodes the 206-amino-acid TAF25p protein. TAF25p is an integral subu nit of both the 15-subunit general transcription factor TFIID and the multi subunit, chromatin-acetylating transcriptional coactivator SAGA. We used hy droxylamine mutagenesis, targeted deletion, alanine-scanning mutagenesis, h igh-copy suppression methods, and two-hybrid screening to dissect TAF25. Te mperature-sensitive mutant strains generated were used for coimmunoprecipit ation and transcription analyses to define the in vivo functions of TAF25p. The results of these analyses show that TAF25p is comprised of multiple mu table elements which contribute importantly to RNA polymerase II-mediated m RNA gene transcription.