title: Thermodynamic characterization of the folding coupled DNA binding by the monomeric transcription activator GCN4 peptide.
abstract: Dimerization is a widely believed critical requirement for the yeast transcriptional activator GCN4 specifically recognizing its DNA target sites. Nonetheless, the binding of the monomeric GCN4 to DNA target sites AP-1 and ATF/CREB was recently detected by kinetic studies. Here, for the first time, we present a detailed description of the thermodynamics of a monomeric peptide GCN4-br, the basic region (226-252) of GCN4, binding to AP-1, and ATF/CREB. GCN4 specifically binds to AP-1 and ATF/CREB in the monomeric form as shown by our circular dichroism thermal unfolding measurements. Isothermal titration calorimetry experiments indicate that the binding process of GCN4-br with DNA is enthalpically driven, accompanied by an unfavorable entropy change. The temperature dependence of DeltaH(0) reveals negative changes in heat capacity DeltaC(p): DeltaC(p) = -0.92 kJ. mol(-1) K(-1) and DeltaC(p) = -0.95 kJ. mol(-1) K(-1) for GCN4-br binding to AP-1 and ATF/CREB, respectively, which is a striking manifestation of GCN4-br specifically recognizing DNA target sites. These thermodynamic characteristics may give new insight into the mechanism by which GCN4 protein binds to DNA target sites for its transcriptional regulation.
authors.affiliation: State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Cao
authors.forename: Aoneng
authors.initials: A
authors.lastname: Cao
authors.forename: Luhua
authors.initials: L
authors.lastname: Lai
mesh_terms: D051698:Activating Transcription Factor 2; D001665:Binding Sites; D017362:Cyclic AMP Response Element-Binding Protein / Q000737:chemistry*; D004268:DNA-Binding Proteins / Q000737:chemistry*; D004735:Energy Transfer; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D011494:Protein Kinases / Q000737:chemistry*; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*; D013696:Temperature; D018808:Transcription Factor AP-1 / Q000737:chemistry*; D014157:Transcription Factors / Q000737:chemistry*
chemical_list: D051698:Activating Transcription Factor 2; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D009841:Oligonucleotides; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D011494:Protein Kinases