Formation of a wrapped DNA-protein interface: experimental characterization and analysis of the large contributions of ions and water to the thermodynamics of binding IHF to H' DNA.

ABSTRACT: To characterize driving forces and driven processes in formation of a large-interface, wrapped protein-DNA complex analogous to the nucleosome, we have investigated the thermodynamics of binding the 34-base pair (bp) H' DNA sequence to the Escherichia coli DNA-remodeling protein integration host factor (IHF). Isothermal titration calorimetry and fluorescence resonance energy transfer are applied to determine effects of salt concentration [KCl, KF, K glutamate (KGlu)] and of the excluded solute glycine betaine (GB) on the binding thermodynamics at 20 degrees C. Both the binding constant K(obs) and enthalpy Delta H degrees (obs) depend strongly on [salt] and anion identity. Formation of the wrapped complex is enthalpy driven, especially at low [salt] (e.g., Delta H(o)(obs)=-20.2 kcal x mol(-

SUBMITTER: Vander Meulen KA 

PROVIDER: S-EPMC2336898 | biostudies-literature | 2008 Mar

REPOSITORIES: biostudies-literature