Two-stage thermal unfolding of [Cys 55]-substituted Cro repressor of bacteriophage λ

• Published in: FEBS letters Vol. 289; no. 2; pp. 201 - 204
• Main Authors: Gitelson, G.I., Griko, Yu.V., Kurochkin, A.V., Rogov, V.V., Kutyshenko, V.P., Kirpichnikov, M.P., Privalov, P.L.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 09.09.1991; Elsevier
• Subjects: 1H NMR; Bacteriophage lambda - genetics; Biological and medical sciences; Calorimetry, Differential Scanning - methods; Cro repressor; Cysteine; DNA-Binding Proteins; Escherichia coli - genetics; Fundamental and applied biological sciences. Psychology; Genes, Synthetic; Genetics; Microbiology; Mutant; Protein Denaturation; Protein Engineering; Repressor Proteins - chemistry; Repressor Proteins - genetics; Scanning calorimetry; S–S bond; SS bond; Thermal denaturation; Transcription Factors - chemistry; Viral Proteins; Viral Regulatory and Accessory Proteins; Virology; Thermal denaturation; 1H NMR; Scanning calorimetry; SS bond; Cro repressor; Mutant; Virus; Gel electrophoresis; Disulfide bond; Siphoviridae; Transcription repressor; NMR spectrometry; Mutation; Phage lambda; Phage
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(91)81069-K

It has been shown by scanning calorimetry and 1H NMR spectroscopy that thermal denaturation of mutant λ phage cro repressor in which Val 55 was substituted for Cys, proceeds in 2 stages in contrast to the wild type protein. At neutral pH values, an additional cooperative transition has been observed at about 100°C. Calorimetric measurements on the mutant and its tryptic fragment lead to the conclusion that the two-stage character of thermal unfolding of the mutant is due to a disruption of an additional cooperative domain in the dimer molecule which is stabilized by the SS crosslink.