DNA RECOGNITION AND SUPERSTRUCTURE FORMATION BY HELIX-TURN-HELIX PROTEINS

The way helix-turn-helix proteins recognize DNA is analysed by compari ng their sequences, structures, and binding specificities. Individual recognition helices in these proteins bind to four DNA base pairs with the same geometry. However, pairs of recognition helices in the prote in dimers can have different separations and orientations, These diffe rences are used for discriminating between DNAs which have different s uperstructures, in particular, different numbers of base pairs between sets of the four base pairs.