Striking conservation of TFIID in Schizosaccharomyces pombe and Saccharomyces cerevisiae.

Eukaryotic promoters contain binding sites for basic transcription factors and gene-specific activator proteins. The transcription factors interact at the TATA box, which lies close to the position of transcription initiation. Activators typically bind to distant sites that can lie kilobases away from the initiation site. The factor TFIID binds specifically to the TATA box to initiate an ordered pathway of assembly of the basic transcription factors. Biochemical analyses have shown that human and Saccharomyces cerevisiae TFIID are functionally interchangeable in vitro. To study further the functional conservation of this critical factor, we are surveying proteins from divergent organisms that can substitute in vivo for the S. cerevisiae TFIID. We report here the isolation of a unique gene from Schizosaccharomyces pombe that fully complements a null mutation in SPT15, the gene that encodes TFIID in S. cerevisiae. The Schiz. pombe gene encodes a protein 93% identical (166/178) to S. cerevisiae TFIID in a region consisting of a direct repeat.