DNA curvature and flexibility in vitro and in vivo

It has been more than 50 years since the elucidation of the structure ofdouble-helical DNA. Despite active research and progress in DNA biology andbiochemistry, much remains to be learned in the field of DNA biophysics. Predicting thesequence-dependent curvature and flexibility of DNA is difficult. Applicability of theconventional worm-like chain polymer model of DNA has been challenged. The fundamentalforces responsible for the remarkable resistance of DNA to bending and twisting remaincontroversial. The apparent ‘ softening ’ of DNA measured in vivo in the presence of kinkingproteins and superhelical strain is incompletely understood. New methods and insights arebeing applied to these problems. This review places current work on DNA biophysics inhistorical context and illustrates the ongoing interplay between theory and experiment in thisexciting field