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

The idea that recruitment of the transcriptional machinery to a promoter suffices for gene activation is based partly on the results of “artificial recruitment” experiments performed in vivo. Artificial recruitment can be effected by a “nonclassical” activator comprising a DNA-binding domain fused to a component of the transcriptional machinery. Here we show that activation by artificial recruitment in yeast can be sensitive to any of three factors: position of the activator-binding elements, sequence of the promoter, and coding sequences downstream of the promoter. In contrast, classical activators worked efficiently at all promoters tested. In all cases the “artificial recruitment” fusions synergized well with classical activators. A classical activator evidently differs from a nonclassical activator in that the 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 studies in mammalian cells in the accompanying paper [Nevado, J., Gaudreau, L., Adam, M. & Ptashne, M. (1999) Proc. Natl. Acad. Sci. USA 96, 2674–2677].