Just wandering around, and came across this stuff, relevant to at least Sangamo and Ariad........
Biochemistry 1999 Aug 17;38(33):10801-7
Anti-repression of RNA polymerase II transcription by pyrrole-imidazole
polyamides.
Dickinson LA, Trauger JW, Baird EE, Ghazal P, Dervan PB, Gottesfeld JM
Department of Molecular Biology, Scripps Research Institute, La Jolla, California 92037, USA.
Pyrrole-imidazole polyamides are ligands that bind in the minor groove of DNA with high affinity and sequence selectivity.
Molecules of this class have been shown to disrupt specific transcription factor-DNA interactions and to inhibit basal and
activated transcription from various RNA polymerase II and III promoters. A set of eight-ring hairpin-motif pyrrole-imidazole
polyamides has been designed to bind within the binding site for the human cytomegalovirus (CMV) UL122 immediate early
protein 2 (IE86). IE86 represses transcription of the CMV major immediate early promoter (MIEP) through its cognate cis
recognition sequence (crs) located between the TATA box and the transcription initiation site. The designed polyamides bind to
their target DNA sequence with nanomolar affinities and with a high degree of sequence selectivity. The polyamides effectively
block binding of IE86 protein to the crs in DNase I footprinting experiments. A mismatch polyamide, containing a single
imidazole to pyrrole substitution, and also a polyamide binding to a site located 14 base pairs upstream of the repressor binding
site, do not prevent IE86 binding to the crs. IE86-mediated transcriptional repression in vitro is relieved by a match polyamide
but not by a mismatch polyamide. Transcription from a DNA template harboring a mutation in the crs is not affected either by
IE86 protein or by the match polyamides. These results demonstrate that this new class of small molecules, the
pyrrole-imidazole polyamides, are not only effective inhibitors of basal and activated transcription, but also can be used to
activate transcription by blocking the DNA-binding activity of a repressor protein. |
