title: Interaction of mutant lambda repressors with operator and non-operator DNA.
abstract: We have described a set of mutations that alter side-chains on the operator binding surface of lambda repressor. In this paper, we study the interactions of 12 purified mutant repressors with operator and non-operator DNA. The mutant proteins have operator affinities that are reduced from tenfold to greater than 10,000-fold compared to wild-type. Nine of the mutants have affinities for non-operator DNA that are similar to wild-type, two mutants show decreased non-specific binding, and one mutant has increased affinity for non-operator DNA. We discuss these findings in terms of the structural and energetic contributions of side-chain--DNA interactions, and show that certain contacts between the repressor and the operator backbone contribute both energy and specificity to the interaction.
mesh_terms: D000595:Amino Acid Sequence; D010582:Bacteriophage lambda / Q000235:genetics*; D003196:Computer Graphics; D003198:Computer Simulation; D004279:DNA, Viral / Q000235:genetics*; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics; D008745:Methylation; D008957:Models, Genetic; D009154:Mutation; D009875:Operator Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D004279:DNA, Viral; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins