Transcriptional activation by artificial recruitment in yeast is influenced by promoter architecture and downstream sequences

The idea that recruitment of the transcriptional machinery to It promoter s uffices far gene activation is based partly on the results of "artificial r ecruitment" experiments performed in vivo.;Artificial recruitment can be ef fected by a "nonclassical'' activator comprising a DNA-binding domain fused to a component of the transcriptional machinery, Here we show that activat ion by artificial recruitment in yeast can be sensitive to any of three fac tors: position of the activator-binding elements, sequence of the promoter. and coding sequences downstream of the promoter. Ln contrast, classical ac tivators worked efficiently at all promoters tested. In all cases the "arti ficial recruitment" fusions synergized well with classical activators. A cl assical activator evidently differs from a nonclassical activator in that t he former can touch multiple sites on the transcriptional machinery, and we propose that that difference accounts for the broader spectrum of activity of the typical classical activator. A similar conclusion is reached from s tudies in mammalian cells in the accompanying paper.