A positioned nucleosome on the human U6 promoter allows recruitment of SNAP(c) by the Oct-1 POU domain

The human snRNA promoters contain a proximal sequence element (PSE) require d for basal transcription and a distal sequence element (DSE) required for activated transcription. The PSE recruits the multisubunit factor SNAP,, wh ereas the DSE recruits Oct-1. Oct-1 and SNAP, bind cooperatively to DNA whe n their respective binding sites are moved into proximity through a mechani sm that involves a defined protein-protein contact. Here, we show that on t he natural U6 promoter, cooperative binding of Oct-1 and SNAP, is mediated by a positioned nucleosome that resides between the DSE and the PSE. This c ooperative binding requires the same protein-protein contact as cooperative binding to closely spaced sites on naked DNA and mediates transcription ac tivation.