Action at a distance: DNA-looping and initiation of transcription.

Effective initiation of transcription, especially in eukaryotes, requires the specific assembly of large protein complexes at promoters. We ask here how activator proteins that are bound hundreds or thousands of base pairs away from the promoter might facilitate this process if protein-protein interactions occur via looping of the intervening DNA. We show that the local concentration at the promoter of activator proteins bound at vicinal DNA sites can be substantially regulated by intrinsic or protein-induced distortion of the regular DNA conformation.