Linked Life Data

9500918

Source:http://linkedlifedata.com/resource/pubmed/id/9500918

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1998-5-4
pubmed:abstractText
We used isothermal titration calorimetry and fluorescence spectroscopy to investigate the thermodynamics of non-sequence-specific DNA-binding by the Sso7d protein from the archaeon Sulfolobus solfataricus. We report the Sso7d-poly(dGdC) binding thermodynamics as a function of buffer composition (Tris-HCl or phosphate), temperature (15 to 45 degrees C), pH (7.1 to 8.0), osmotic stress and solvent (H2O/2H2O), and compare it to poly (dAdT) binding; and we have previously also reported the salt concentration dependence. Binding isotherms can be represented by the McGhee-von Hippel model for non-cooperative binding, with a binding site size of four to five DNA base-pairs and binding free energies in the range DeltaG degrees approximately -7 to DeltaG degrees approximately -10 kcal mol-1, depending on experimental conditions. The non-specific nature of the binding is reflected in similar thermodynamics for binding to poly(dAdT) and poly(dGdC). The native lysine methylation of Sso7d has only minor effects on the binding thermodynamics. Sso7d binding to poly(dGdC) is endothermic at 25 degrees C with a binding enthalpy DeltaH degrees approximately 10 kcal mol-1 in both phosphate and Tris-HCl buffers at pH 7.6, indicating that DeltaH degrees does not include large contributions from coupled buffer ionization equilibria at this pH. The binding enthalpy is temperature dependent with a measured heat capacity change DeltaCp degrees=-0.25(+/-0.01) kcal mol-1 K-1 and extrapolations of thermodynamic data indicate that the complex is heat stable with exothermic binding close to the growth temperature (75 to 80 degreesC) of S. solfataricus. Addition of neutral solutes (osmotic stress) has minor effects on DeltaG degrees and the exchange of H2O for 2H2O has only a small effect on DeltaH degrees, consistent with the inference that complex formation is not accompanied by net changes in surface hydration. Thus, other mechanisms for the heat capacity change must be found. The observed thermodynamics is discussed in relation to the nature of non-sequence-specific DNA-binding by proteins.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0022-2836
pubmed:author
pubmed:copyrightInfo
Copyright 1998 Academic Press Limited.
pubmed:issnType
Print
pubmed:day
6
pubmed:volume
276
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
775-86
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:9500918-Archaeal Proteins, pubmed-meshheading:9500918-Base Sequence, pubmed-meshheading:9500918-Binding Sites, pubmed-meshheading:9500918-Calorimetry, pubmed-meshheading:9500918-DNA, Archaeal, pubmed-meshheading:9500918-DNA-Binding Proteins, pubmed-meshheading:9500918-Deuterium Oxide, pubmed-meshheading:9500918-Hydrogen-Ion Concentration, pubmed-meshheading:9500918-Lysine, pubmed-meshheading:9500918-Macromolecular Substances, pubmed-meshheading:9500918-Methylation, pubmed-meshheading:9500918-Osmotic Pressure, pubmed-meshheading:9500918-Poly dA-dT, pubmed-meshheading:9500918-Polydeoxyribonucleotides, pubmed-meshheading:9500918-Protein Binding, pubmed-meshheading:9500918-Spectrometry, Fluorescence, pubmed-meshheading:9500918-Sulfolobus, pubmed-meshheading:9500918-Temperature, pubmed-meshheading:9500918-Thermodynamics, pubmed-meshheading:9500918-Water
pubmed:year
1998
pubmed:articleTitle
Thermodynamic characterization of non-sequence-specific DNA-binding by the Sso7d protein from Sulfolobus solfataricus.
pubmed:affiliation
Department of Biosciences, Karolinska Institute, Huddinge, Sweden.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't