DNA SELF-FITTING - THE DOUBLE HELIX DIRECTS THE GEOMETRY OF ITS SUPRAMOLECULAR ASSEMBLY

Groove-backbone interaction is a natural and biologically relevant mec hanism for the specific assembly of B-DNA double helices. Crystal engi neering and crystal packing analysis of oligonucleotides of different sizes and sequences reveal that the sequence-dependent self-fitting of B-DNA helices is a dominant constraint for their ordered assembly. It can override the other intermolecular interactions and impose the ove rall geometry of the packing. Analysis of experimental examples of arc hitectural motifs formed by the geometric combination of self-fitted D NA segments leads to general rules for DNA assembly. Like a directing piece for a supramolecular 'construction set', the double helix impose s a limited number of geometric solutions. These basic architectural c onstraints could direct, in a codified manner, the formation of higher -order structures. DNA architectural motifs exhibit new structural and electrostatic properties which could have some implications for their molecular recognition by proteins acting on DNA.