Influence of the base sequence on the free B-DNA intrinsic flexibility.

The DNA sequence is expressed in terms of the 10 complementary dinucleotides base steps, as summarized here from a previous study (Heddi et al., 2010b). The intrinsic flexibility of each complementary dinucleotide is quantified by its TRX score (STRX), i.e. the half-sum of the average BII percentages (%BII) observed in solution by NMR for its two facing phosphates. The higher the TRX score, the greater the intrinsic flexibility of the step, especially in terms of the helicoidal parameters twist, roll and X-displacement. The maximal theoretical flexibility corresponds to a TRX score of 50 (50% of time in BI, 50% of time in BII). The average standard deviation of %BII is ±8.