Transcription activation: unveiling the essential nature of TFIID

The TAF subunits of TFIID mediate activation of subsets of the eukaryotic genome. Recent results demonstrate that TFIID is recruited to promoters in an activator-specific manner involving functional interaction between upstream regulatory elements and the core promoter, thereby coordinating the expression of distinct sets of genes.     

Functional dissection of Escherichia coli promoters: information in the transcribed region is involved in late steps of the overall process.

After binding to a promoter Escherichia coli RNA polymerase is in contact with a region of about 70 bp. Around 20 bp of this sequence are transcribed. Information encoded within this transcribed region is involved in late steps of the functional program of a promoter. By changing such 'down-stream' sequences promoter strength in vivo can be varied more than 10-fold. By contrast, information for early steps of the promoter program such as recognition by the enzyme and formation of a stable complex resides in a central core region of about 35 bp. Our data show that the strength of a promoter can be limited at different levels of the overall process. Consequently promoters of identical strength can exhibit different structures due to an alternate optimization of their program.