title: Combining thermostable mutations increases the stability of lambda repressor.
abstract: We have combined three mutations previously shown to stabilize lambda repressor against thermal denaturation. Two of these mutations are in helix 3, where Gly-46 and Gly-48 have been replaced by alanines [Hecht, M. H., et al. (1986) Proteins: Struct., Funct., Genet. 1, 43-46]. The other mutation, which replaces Tyr-88 with cysteine, allows the protein to form an intersubunit disulfide bond [Sauer, R. T., et al. (1986) Biochemistry 25, 5992-5998]. Calorimetric measurements show that the two alanine substitutions stabilize repressor by about 8 degrees C, that the disulfide bond stabilizes repressor by about 8 degrees C, and that the triple mutant is 16 degrees C more stable than wild-type repressor.
authors.affiliation: Department of Biophysics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
authors.forename: R S
authors.initials: RS
authors.lastname: Stearman
authors.forename: A D
authors.initials: AD
authors.lastname: Frankel
authors.forename: E
authors.initials: E
authors.lastname: Freire
authors.forename: B S
authors.initials: BS
authors.lastname: Liu
authors.forename: C O
authors.initials: CO
authors.lastname: Pabo
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002152:Calorimetry, Differential Scanning; D004268:DNA-Binding Proteins; D004355:Drug Stability; D004926:Escherichia coli / Q000235:genetics; D006358:Hot Temperature; D008969:Molecular Sequence Data; D009154:Mutation; D011489:Protein Denaturation; D012097:Repressor Proteins / Q000235:genetics; D013816:Thermodynamics; D014157:Transcription Factors / Q000235:genetics; 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