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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
10
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pubmed:dateCreated |
2009-5-19
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pubmed:abstractText |
HMGA2 is a DNA minor-groove binding protein. We previously demonstrated that HMGA2 binds to AT-rich DNA with very high binding affinity where the binding of HMGA2 to poly(dA-dT)(2) is enthalpy-driven and to poly(dA)poly(dT) is entropy-driven. This is a typical example of enthalpy-entropy compensation. To further study enthalpy-entropy compensation of HMGA2, we used isothermal-titration-calorimetry to examine the interactions of HMGA2 with two AT-rich DNA hairpins: 5'-CCAAAAAAAAAAAAAAAGCCCCCGCTTTTTTTTTTTTTTTGG-3' (FL-AT-1) and 5'-CCATATATATATATATAGCCCCCGCTATATATATATATATGG-3' (FL-AT-2). Surprisingly, we observed an atypical isothermal-titration-calorimetry-binding curve at low-salt aqueous solutions whereby the apparent binding-enthalpy decreased dramatically as the titration approached the end. This unusual behavior can be attributed to the DNA-annealing coupled to the ligand DNA-binding and is eliminated by increasing the salt concentration to approximately 200 mM. At this condition, HMGA2 binding to FL-AT-1 is entropy-driven and to FL-AT-2 is enthalpy-driven. Interestingly, the DNA-binding free energies for HMGA2 binding to both hairpins are almost temperature independent; however, the enthalpy-entropy changes are dependent on temperature, which is another aspect of enthalpy-entropy compensation. The heat capacity change for HMGA2 binding to FL-AT-1 and FL-AT-2 are almost identical, indicating that the solvent displacement and charge-charge interaction in the coupled folding/binding processes for both binding reactions are similar.
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pubmed:grant |
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pubmed:commentsCorrections |
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
May
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pubmed:issn |
1542-0086
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pubmed:author |
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pubmed:issnType |
Electronic
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pubmed:day |
20
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pubmed:volume |
96
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
4144-52
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pubmed:dateRevised |
2010-9-24
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pubmed:meshHeading |
pubmed-meshheading:19450485-AT Rich Sequence,
pubmed-meshheading:19450485-Animals,
pubmed-meshheading:19450485-Base Sequence,
pubmed-meshheading:19450485-Buffers,
pubmed-meshheading:19450485-Calorimetry, Differential Scanning,
pubmed-meshheading:19450485-DNA,
pubmed-meshheading:19450485-Deoxyribonucleotides,
pubmed-meshheading:19450485-Entropy,
pubmed-meshheading:19450485-HMGA2 Protein,
pubmed-meshheading:19450485-Inverted Repeat Sequences,
pubmed-meshheading:19450485-Nucleic Acid Denaturation,
pubmed-meshheading:19450485-Protein Binding,
pubmed-meshheading:19450485-Sodium Chloride,
pubmed-meshheading:19450485-Solutions,
pubmed-meshheading:19450485-Titrimetry,
pubmed-meshheading:19450485-Transition Temperature
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pubmed:year |
2009
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pubmed:articleTitle |
Binding the mammalian high mobility group protein AT-hook 2 to AT-rich deoxyoligonucleotides: enthalpy-entropy compensation.
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pubmed:affiliation |
Department of Chemistry & Biochemistry, Florida International University, Miami, Florida 33199, USA.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, Non-P.H.S.,
Research Support, N.I.H., Extramural
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