Vladimir Bondarenko, Ye Liu,  Alexander Ninfa ¹ and Vasily M. Studitsky*

Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, 540 East Canfield Avenue, Room 5123, Detroit, MI 48201, USA, and
¹ Department of Biological Chemistry, University of Michigan Medical School, 1301 Catherine Road, Ann Arbor, MI 48109-0606, USA

* To whom correspondence should be addressed.   Tel: +1 313 993 7818;   Fax: +1 313 577 2765;
Email:   vstudit@med.wayne.edu

The mechanism by which an enhancer activates transcription over large distances has been investigated. Activation of the glnAp2 promoter by the NtrC-dependent enhancer in Escherichia coli was analyzed using a purified system supporting multiple-round transcription in vitro. Our results suggest that the enhancer–promoter interaction and the initiation complex must be formed de novo during every round of transcription. No protein remained bound to the promoter after RNA polymerase escaped into elongation. Furthermore, the rate of initiation during the first and subsequent rounds of transcription were very similar, suggesting that there was no functional ‘memory’ facilitating multiple rounds of transcription. These studies exclude the hypothesis that enhancer action during multiple-round transcription involves the memory of the initial activation event.

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3. Frenster JH, "Activation of DNA Transcription within Repressed Chromatin".