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Effect of mutation of the Sac7d intercalating residues on the temperature dependence of DNA distortion and binding thermodynamics.
Biochemistry. 2005 Mar 29; 44(12):4794-804.B

Abstract

Sac7d is a small chromatin protein from the hyperthermophile Sulfolobus acidocaldarius which kinks duplex DNA by approximately 66 degrees at a single base pair step with intercalation of V26 and M29 side chains. Site-directed mutagenesis coupled with calorimetric and spectroscopic data has been used to characterize the influence of the intercalating side chains on the structure and thermodynamics of the DNA complex from 5 to 85 degrees C. Two single-alanine substitutions (V26A and M29A) and five double-glycine, -alanine, -leucine, -phenylalanine, and -tryptophan substitutions of the surface residues have been created. NMR and fluorescence titrations indicated that the substitutions had little effect on the structure of the protein or DNA binding site size. Each of the mutant proteins demonstrated a temperature-dependent binding enthalpy which was correlated with a similar temperature dependence in the structure of the complex reflected by changes in fluorescence and circular dichroism. A positive heat capacity change (DeltaC(p)) for DNA binding was observed for only those mutants which also demonstrated a thermotropic structural transition in the complex, and the temperature range for the positive DeltaC(p) coincided with that observed for the structural transition. The thermodynamic data are interpreted using a model in which binding is linked to an endothermic distortion of the DNA in the complex. The results support the proposal that the unfavorable enthalpy of binding of Sac7d at 25 degrees C is due in part to the distortion of DNA.

Authors+Show Affiliations

Peters WB
Laboratory for Structural Biology, Departments of Chemistry and Biological Sciences, Graduate Program in Biotechnology and Bioengineering, University of Alabama, Huntsville, Alabama 35899, USA.
Edmondson SP
No affiliation info available
Shriver JW
No affiliation info available

MeSH

Archaeal ProteinsBinding SitesCalorimetryCircular DichroismDNADNA-Binding ProteinsIntercalating AgentsMethionineMutagenesis, Site-DirectedNucleic Acid ConformationNucleic Acid HeteroduplexesProtein BindingProtein Structure, SecondarySpectrometry, FluorescenceSulfolobus acidocaldariusTemperatureThermodynamicsValine

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

15779906

Citation

Peters, William B., et al. "Effect of Mutation of the Sac7d Intercalating Residues On the Temperature Dependence of DNA Distortion and Binding Thermodynamics." Biochemistry, vol. 44, no. 12, 2005, pp. 4794-804.
Peters WB, Edmondson SP, Shriver JW. Effect of mutation of the Sac7d intercalating residues on the temperature dependence of DNA distortion and binding thermodynamics. Biochemistry. 2005;44(12):4794-804.
Peters, W. B., Edmondson, S. P., & Shriver, J. W. (2005). Effect of mutation of the Sac7d intercalating residues on the temperature dependence of DNA distortion and binding thermodynamics. Biochemistry, 44(12), 4794-804.
Peters WB, Edmondson SP, Shriver JW. Effect of Mutation of the Sac7d Intercalating Residues On the Temperature Dependence of DNA Distortion and Binding Thermodynamics. Biochemistry. 2005 Mar 29;44(12):4794-804. PubMed PMID: 15779906.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of mutation of the Sac7d intercalating residues on the temperature dependence of DNA distortion and binding thermodynamics. AU - Peters,William B, AU - Edmondson,Stephen P, AU - Shriver,John W, PY - 2005/3/23/pubmed PY - 2005/6/10/medline PY - 2005/3/23/entrez SP - 4794 EP - 804 JF - Biochemistry JO - Biochemistry VL - 44 IS - 12 N2 - Sac7d is a small chromatin protein from the hyperthermophile Sulfolobus acidocaldarius which kinks duplex DNA by approximately 66 degrees at a single base pair step with intercalation of V26 and M29 side chains. Site-directed mutagenesis coupled with calorimetric and spectroscopic data has been used to characterize the influence of the intercalating side chains on the structure and thermodynamics of the DNA complex from 5 to 85 degrees C. Two single-alanine substitutions (V26A and M29A) and five double-glycine, -alanine, -leucine, -phenylalanine, and -tryptophan substitutions of the surface residues have been created. NMR and fluorescence titrations indicated that the substitutions had little effect on the structure of the protein or DNA binding site size. Each of the mutant proteins demonstrated a temperature-dependent binding enthalpy which was correlated with a similar temperature dependence in the structure of the complex reflected by changes in fluorescence and circular dichroism. A positive heat capacity change (DeltaC(p)) for DNA binding was observed for only those mutants which also demonstrated a thermotropic structural transition in the complex, and the temperature range for the positive DeltaC(p) coincided with that observed for the structural transition. The thermodynamic data are interpreted using a model in which binding is linked to an endothermic distortion of the DNA in the complex. The results support the proposal that the unfavorable enthalpy of binding of Sac7d at 25 degrees C is due in part to the distortion of DNA. SN - 0006-2960 UR - https://www.unboundmedicine.com/medline/citation/15779906/Effect_of_mutation_of_the_Sac7d_intercalating_residues_on_the_temperature_dependence_of_DNA_distortion_and_binding_thermodynamics_ DB - PRIME DP - Unbound Medicine ER -