A basic tail increases repression by dimeric lac repressor.

P Kolkhof; S Oehler; R Alex; B Müller-Hill

doi:10.1006/jmbi.1994.0148

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A basic tail increases repression by dimeric lac repressor.

P Kolkhof·S Oehler·R Alex·B Müller-Hill

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Abstract

Tetrameric Lac repressor achieves cooperative repression by binding simultaneously to O1 and to one of the auxiliary operators O2 or O3, thereby forcing the intervening DNA into a loop. Dimeric Lac repressor is not able to form DNA loops and consequently shows no cooperative repression. We constructed a dimeric Lac repressor mutant which exhibits increased repression to the lac operon that does not depend on specific operator-repressor-operator loops. This Lac repressor carries a synthetic tail of basic residues attached to its C terminus. With this construct, we observe an increase of the in vivo repression upon addition of auxiliary lac operators to a chromosomal lac operon controlled by O1. This suggests that the basic tail enables dimeric Lac repressor to enhance its repression by additional non-specific DNA contacts.

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Amino Acid Sequence DNA, Bacterial Escherichia coli Lac Operon Molecular Sequence Data Nucleic Acid Conformation Operator Regions, Genetic Protein Binding Protein Conformation Protein Engineering Recombinant Fusion Proteins Repressor Proteins Structure-Activity Relationship Journal Article Research Support, Non-U.S. Gov't

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P Kolkhof, S Oehler, R Alex, B Müller-Hill. 1995-03-31. A basic tail increases repression by dimeric lac repressor.. https://doi.org/10.1006/jmbi.1994.0148

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