title: Increasing and decreasing protein stability: effects of revertant substitutions on the thermal denaturation of phage lambda repressor.
abstract: The thermal denaturations of five revertant lambda repressors containing single amino acid substitutions in their N-terminal domains have been studied by differential scanning calorimetry. Two substitutions slightly decrease stability, and the remaining three render the protein more stable than wild type. The Gly48----Asn and Gly48----Ser proteins are 4 degrees C more stable than wild type. These two substitutions replace an alpha helical residue, and in each case a poor helix forming residue, glycine, is replaced by a residue with a higher helical propensity. We also present data showing that one revertant, Tyr22----Phe, has reduced operator DNA binding affinity despite its enhanced stability.
mesh_terms: D000595:Amino Acid Sequence; D003460:Crystallization; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D006358:Hot Temperature; D006860:Hydrogen Bonding; D009154:Mutation; D009875:Operator Regions, Genetic; D011489:Protein Denaturation; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins; D004247:DNA