PREDICTION OF QUATERNARY STRUCTURE OF COILED COILS - APPLICATION TO MUTANTS OF THE GCN4 LEUCINE-ZIPPER

Using a simplified protein model, the equilibrium between different ol igomeric species of the wild-type GCN4 leucine zipper and seven of its mutants have been predicted. Over the entire experimental concentrati on range, agreement with experiment is found in five cases, while in t wo cases agreement is found over a portion of the concentration range. These studies demonstrate a methodology for predicting coiled coil qu aternary structure and allow for the dissection of the interactions re sponsible for the global fold. In agreement with the conclusion of Har bury et al., the results of the simulations indicate that the pattern of hydrophobic and hydrophilic residues alone is insufficient to defin e a protein's three-dimensional structure. In addition, these simulati ons indicate that the degree of chain association is determined by the balance between specific side-chain packing preferences and the entro py reduction associated with side-chain burial in higher-order multime rs.