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Stability and flexibility in the structure of the hyperthermophile DNA-binding protein Sac7d.
Biochemistry. 2005 Oct 18; 44(41):13500-9.B

Abstract

Sac7d is a chromatin protein from the hyperthermophile Sulfolobus acidocaldarius that severely kinks duplex DNA with negligible change in protein structure. In previous work, the overall stability of Sac7d has been well-characterized with a global analysis of the linkage of folding, protonation, and anion binding. We extend that work here with NMR measurements of global stability as well as the distribution of stability and flexibility in the solution structure. Native state amide hydrogen exchange has been used to identify the most-protected core amide protons which exchange through global unfolding. The pH and temperature dependence of stability defined by native state exchange is in excellent agreement with the free energy surface determined by a linkage analysis of the dependence of folding on pH, salt, and temperature. These results confirm that the deltaC(P) obtained from a Kirchhoff analysis of DSC data (i.e., deltaH vs Tm) is incorrect, and an accurate description of the protein stability curve for Sac7d requires a measure of the thermodynamic contributions of protonation and anion binding. Amide hydrogen exchange, along with generalized order parameters determined by 15N relaxation data, demonstrates considerable variation in stability throughout the structure with some of the least stable regions occurring at the N- and C-termini. The most stable and inflexible region of the backbone occurs primarily in the DNA-binding beta-sheet which is responsible for bending DNA.

Authors+Show Affiliations

Laboratory for Structural Biology, Department of Chemistry, University of Alabama in Huntsville, Huntsville, Alabama 35899, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

16216073

Citation

Kahsai, Mebrahtu A., et al. "Stability and Flexibility in the Structure of the Hyperthermophile DNA-binding Protein Sac7d." Biochemistry, vol. 44, no. 41, 2005, pp. 13500-9.
Kahsai MA, Martin E, Edmondson SP, et al. Stability and flexibility in the structure of the hyperthermophile DNA-binding protein Sac7d. Biochemistry. 2005;44(41):13500-9.
Kahsai, M. A., Martin, E., Edmondson, S. P., & Shriver, J. W. (2005). Stability and flexibility in the structure of the hyperthermophile DNA-binding protein Sac7d. Biochemistry, 44(41), 13500-9.
Kahsai MA, et al. Stability and Flexibility in the Structure of the Hyperthermophile DNA-binding Protein Sac7d. Biochemistry. 2005 Oct 18;44(41):13500-9. PubMed PMID: 16216073.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Stability and flexibility in the structure of the hyperthermophile DNA-binding protein Sac7d. AU - Kahsai,Mebrahtu A, AU - Martin,Ewan, AU - Edmondson,Stephen P, AU - Shriver,John W, PY - 2005/10/12/pubmed PY - 2006/3/15/medline PY - 2005/10/12/entrez SP - 13500 EP - 9 JF - Biochemistry JO - Biochemistry VL - 44 IS - 41 N2 - Sac7d is a chromatin protein from the hyperthermophile Sulfolobus acidocaldarius that severely kinks duplex DNA with negligible change in protein structure. In previous work, the overall stability of Sac7d has been well-characterized with a global analysis of the linkage of folding, protonation, and anion binding. We extend that work here with NMR measurements of global stability as well as the distribution of stability and flexibility in the solution structure. Native state amide hydrogen exchange has been used to identify the most-protected core amide protons which exchange through global unfolding. The pH and temperature dependence of stability defined by native state exchange is in excellent agreement with the free energy surface determined by a linkage analysis of the dependence of folding on pH, salt, and temperature. These results confirm that the deltaC(P) obtained from a Kirchhoff analysis of DSC data (i.e., deltaH vs Tm) is incorrect, and an accurate description of the protein stability curve for Sac7d requires a measure of the thermodynamic contributions of protonation and anion binding. Amide hydrogen exchange, along with generalized order parameters determined by 15N relaxation data, demonstrates considerable variation in stability throughout the structure with some of the least stable regions occurring at the N- and C-termini. The most stable and inflexible region of the backbone occurs primarily in the DNA-binding beta-sheet which is responsible for bending DNA. SN - 0006-2960 UR - https://www.unboundmedicine.com/medline/citation/16216073/Stability_and_flexibility_in_the_structure_of_the_hyperthermophile_DNA_binding_protein_Sac7d_ L2 - https://doi.org/10.1021/bi051167d DB - PRIME DP - Unbound Medicine ER -