Nucleic Acids Research Advance Access published online on March 16, 2008
Nucleic Acids Research, doi:10.1093/nar/gkn119
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Molecular Biology |
Autoregulation of the Escherichia coli melR promoter: repression involves four molecules of MelR
1School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT and 2The University of Nottingham, Centre for Biomolecular Sciences, University Park, Nottingham NG7 2RD, UK
*To whom correspondence should be addressed. Tel: (+44) 121 414 5439; Fax: (+44) 121 414 5925; Email: s.j.w.busby{at}bham.ac.uk
Received December 20, 2007. Revised February 29, 2008. Accepted March 3, 2008.
The Escherichia coli MelR protein is a transcription activator that autoregulates its own promoter by repressing transcription initiation. Optimal repression requires MelR binding to a site that overlaps the melR transcription start point and to upstream sites. In this work, we have investigated the different determinants needed for optimal repression and their spatial requirements. We show that repression requires a complex involving four DNA-bound MelR molecules, and that the global CRP regulator plays little or no role.