Structural Studies of Protein-Nucleic Acid Interactions

Recently the structures of three proteins that regulate gene expression have been determined: the ero repressor protein from bacteriophage A, the cI or A repressor protein, also from phage A, and the catabolite gene activator protein from Escherichia coli. Each of these proteins binds specifically to sites on double-stranded DNA that are distinguished by the sequence of base pairs within the binding region. Knowledge of these structures has thrown new light on many of the important aspects of gene regulation, including gene repression, gene activation, the role of allosteric effectors, and protein-protein and protein-DNA interaction. Furthermore, it has been found that, notwithstanding substantial differences in the structure and function of these three proteins, they have a striking structural correspondence within their presumed DNA-binding regions. It is therefore timely to review recent progress in this area.