ACTIVATION OF A DUAL ADENOVIRUS PROMOTER CONTAINING NONCONSENSUS TATAMOTIFS IN SCHIZOSACCHAROMYCES-POMBE - ROLE OF TATA SEQUENCES IN THE EFFICIENCY OF TRANSCRIPTION

The role of TATA elements in the expression of a mammalian promoter wa s investigated in the fission yeast Schizosaccharomyces pombe, by stud ying the human adenovirus E2-early promoter. This is a unique dual pro moter with two nonconsensus TATA elements directing transcription from two cap sites, + 1 and - 26. A sequence TTAAGA provides the TATA box function for the + 1 promoter, whereas a sequence TAAATT, with a close r resemblance to the consensus (TATAA/TA) provides this function for t he - 26 promoter. Yet, in human cells, the + 1 promoter is transcribed about 20 fold more efficiently than the - 26 promoter. We found that both promoters are transcribed faithfully in S.pombe with start sites identical or close to those found in human cells. Surprisingly, the re lative ratio of expression for the + 1 and - 26 promoters was exactly reversed in S.pombe cells. This reversal appeared to be due to the rel atively weak binding of S.pombe TATA binding protein to the TTAAGA mot if, rather than to its rate of dissociation. Furthermore, we show that in S.pombe, promoter expression correlates well with the nucleotide s equence of the TATA element rather than the context in which it is pla ced. By contrast, it is the context of the TATA element, rather than i ts nucleotide sequence that appears to be critical for promoter expres sion in human cells. Our data suggest the existence of one or more add itional factors in human cells that permit the utilization of nonconse nsus TATA elements. S.pombe appears to lack these factors.