Periodical polydeoxynucleotides and DNA curvature.

A theoretical method to predict DNA curvature was developed, and a strikingly good correlation between the experimental retardations and theoretical curvature of all the periodical biosynthetic DNAs so far reported in the literature was found. The analysis has been extended to G- and C-rich synthetic polynucleotides, which show a behavior in agreement with the theoretical prediction. A possible application of the method to biologically significant DNA tracts is shown in the case of the regulative region of one of the genes which code for the small subunit of ribulose-1,5-bisphosphate carboxylase in Pisum sativum. While curvature measurements have not so far been reported for this system, biochemical analysis has indicated short nucleotide sequences (boxes I-III) as recognition sites for regulative proteins. On the basis of the theoretical curvature profile of the region and of the electrophoretic retardation measurements of synthetic polynucleotides, obtained by ligating monomers mimicking the boxes, we suggest that the proteins could use DNA local curvature as structural motif in the recognition process.