Effects of DNA binding and metal substitution on the dynamics of the GAL4 DNA-binding domain as studied by amide proton exchange. |
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| Authors: | T. Mau J. D. Baleja G. Wagner |
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| Affiliation: | Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115. |
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| Abstract: | Backbone amide proton exchange rates in the DNA-binding domain of GAL4 have been determined using 1H-15N heteronuclear correlation NMR spectroscopy. Three forms of the protein were studied-the native Zn-containing protein, the Cd-substituted protein, and a Zn-GAL4/DNA complex. Exchange rates in the Zn-containing protein are significantly slower than in the Cd-substituted protein. This shows that Cd-substituted GAL4 is destabilized relative to the native Zn-containing protein. Upon DNA binding, global retardation of amide proton exchange with solvent was observed, indicating that internal fluctuations of the DNA-recognition module are significantly reduced by the presence of DNA. In all forms of the protein, the internal dyad symmetry of the DNA-recognition module of GAL4 is reflected by the backbone amide proton exchange rates. |
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