Genetic selection for mutations that impair the co-operative binding of lambda repressor |
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Authors: | Nicholas Benson Curtis Adams Philip Youderian |
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Affiliation: | Department of Biological Sciences, University of Southern California, Los Angeles, California 90069-1481, USA. |
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Abstract: | Bacteriophage λ repressor binds co-operatively to adjacent pairs of DNA target sites. A novel combination of positive genetic selections, involving two different operon fusions derived from P22 challenge phages, was used to isolate mutant λ repressors that have lost the ability to bind co-operatively to tandem sites yet retain the ability to bind a strong, single site. These cb (co-operative binding) mutations result in 10 different amino acid changes, which define eight residues in the carboxyl-terminus of repressor. Because challenge phage derivatives may be applied to study essentially any specific protein-DNA interaction, analogous combinations of genetic selections may be used to explore the ways that a variety of proteins interact to assemble regulatory complexes. |
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