tailieunhanh - Báo cáo khoa học: Thermodynamic analysis of Jun–Fos coiled coil peptide antagonists

Dimerization of the Jun–Fos activator protein-1 (AP-1) transcriptional reg-ulator is mediated by coiled coil regions that facilitate binding of the basic regions to a specific promoter. AP-1 is responsible for the regulation of a number of genes involved in cell proliferation. | IFEBS Journal Thermodynamic analysis of Jun-Fos coiled coil peptide antagonists Inferences for optimization of enthalpic binding forces Jonathan A. R. Worrall and Jody M. Mason Department of BiologicalSciences University of Essex Colchester UK Keywords activator protein-1 coiled coil isothermal titration calorimetry jun-fos protein design Correspondence J. M. Mason Department of Biological Sciences University of Essex Wivenhoe Park Colchester CO4 3SQ UK Fax 44 1206 872592 Tel 44 1206 873010 E-mail jmason@ Received 23 August 2010 revised 12 November 2010 accepted 7 December 2010 doi Dimerization of the Jun-Fos activator protein-1 AP-1 transcriptional regulator is mediated by coiled coil regions that facilitate binding of the basic regions to a specific promoter. AP-1 is responsible for the regulation of a number of genes involved in cell proliferation. We have previously derived peptide antagonists and demonstrated them to be capable of binding to the Jun or Fos coiled coil region with high affinity KD values in the low nM range relative to IM for the wild-type interaction . Use of isothermal titration calorimetry combined with CD spectroscopy is reported to elucidate the thermodynamic parameters that drive the interaction stability of peptide antagonists with their cJun and cFos targets. We observe that the free energy of binding for antagonist-target complexes is dominated by the enthalpic term is opposed by unfavourable entropic contributions consistent with reduced conformational freedom and that these values in turn correlate well r with the measured helicity of each dimeric pair. The more helical the antagonist-target complex the more favourable the change in enthalpy which is in turn opposed more strongly by entropy. Antagonistic peptides are predicted to represent excellent scaffolds for further refinement. By contrast the wild-type cJun-cFos complex is dominated by a favourable entropic contribution owing .