A TATA-binding protein mutant defective for TFIID complex formation in vivo

Using an intragenic complementation screen, we have identified a temperatur e-sensitive TATA-binding protein (TBP) mutant (K151L, K156Y) that is defect ive for interaction with certain yeast TBP-associated factors (TAFs) at the restrictive temperature. The K151L,K156Y mutant appears to be functional f or RNA polymerase I (Pol I) and Pol III transcription, and it is capable of supporting Gal4-activated and Gcn4-activated transcription by Pol II. Howe ver, transcription from certain TATA-containing and TATA-less Pot II promot ers is reduced at the restrictive temperature. Immunoprecipitation analysis of extracts prepared after culturing cells at the restrictive temperature for 1 h indicates that the K151L,K156Y derivative is severely compromised i n its ability to interact with TAF130, TAF90, TAF68/61, and TAF25 while rem aining functional for interaction with TAF60 and TAF30, Thus, a TBP mutant that is compromised in its ability to form TFIID can support the response t o Gcn4 but is defective for transcription from specific promoters in vivo.