Energetic coupling between DNA bending and base pair opening.

The pathway for base pair opening within a B-DNA duplex is investigated by theoretical molecular modeling. The results show that the disruption of a single base pair is energetically compatible with the deductions made from hydrogen exchange measurements. In addition, it is found that the opening process is greatly facilitated by DNA bending and that, conversely, once a base pair is disrupted, DNA can bend very easily. It appears that the energetic coupling between these two processes may play an important role in many biological reactions involving nucleic acid distortion.