The immunoglobulin mu enhancer core establishes local factor access in nuclear chromatin independent of transcriptional stimulation.

Factor access in chromatin has been proposed to be facilitated by transcriptional enhancers. With the aim of uncoupling factor access from transcriptional stimulation by protein-protein contacts, we analyzed the potential of enhancer fragments to confec accessibility upon a linked promoter for prokaryotic T7 RNA polymerase. Access to the T7 promoter in pre-B cells from transgenic mice was examined by transcribing chromatin of isolated nuclei with T7 RNA polymerase. A 95-bp immunoglobulin μ enhancer core element was necessary and sufficient to confer accessibility upon the T7 promoter independent of its chromosomal position