The acidic transcriptional activator GAL-VP16 acts on preformed template-committed complexes
White, J.; Brou, C.; Wu, J.; Lutz, Y.; Moncollin, V.; Chambon, P.
EMBO Journal 11(6): 2229-2240
1992
ISSN/ISBN: 0261-4189 PMID: 1376247 Document Number: 400857
The action of the chimeric acidic transcriptional activator GAL-VP16 has been investigated by performing a series of kinetic experiments using the detergent Sarkosyl as well as monoclonal antibodies which specifically inhibit GAL-VP16 DNA binding and transcriptional activation. GAL-VP16 binds to recognition site rapidly, remains bound after transcriptional initiation and is required to maintain stimulated levels of reinitiation. GAL-VP16 action, which appears to result in an increase in the number of preinitiation complexes formed, occurs after the formation of template-committed complexes composed of promoter-bound TFIIA (STF) and a partially purified TFIID fraction conferring GAL-VP16 responsiveness on a reconstituted basal transcription system. This TFIID fraction cannot be replaced by TFIIB or cloned TFIID. Our results suggest that GAL-VP16 activates step(s) in preinitiation complex assembly occurring after TFIID has bound.