A central issue in gene regulation is the mechanism, and biological function, of the cooperative binding of regulatory protein ligands to specific sites on DNA. To elucidate the physical-chemical basis of these interactions we have developed a thermodynamically rigorous method for conducting DNase I 'footprint' (protection) titration experiments. The intrinsic binding constants and also those for cooperative interactions between various sites can be resolved from the individual-site binding curves determined by this technique. Experimental studies of cI-repressor-operator binding have demonstrated that the method provides an accurate representation of the fractional saturation of a binding site. We present individual-site binding curves for a λ operator with two competent sites that demonstrate the presence of cooperative interactions between the sites. These curves set a lower limit to the magnitude of the cooperative free energy without comparison to single-site mutant operators.
|Original language||English (US)|
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|Publication status||Published - Jan 1 1986|
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