Sequence-dependent B<-->A transition in DNA evaluated with dimeric and trimeric scales.

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• DNA exists in different conformations, notably the B and A forms.
• The transition between these forms is influenced by DNA sequence.
• Understanding these conformational changes is crucial for DNA-protein interactions.

Purpose of the Study:

• To develop accurate scales predicting the B-DNA to A-DNA conformational transition.
• To investigate sequence-dependent propensities for DNA conformations.
• To identify sequence motifs that favor specific DNA forms.

Main Methods:

• Experimental characterization of 24 oligo- and polymeric DNA duplexes.
• Determination of free energy differences between B and A forms in solution.
• Development and comparison of dimeric and trimeric sequence scales.

Main Results:

• Developed optimal dimeric and trimeric scales for the DNA B<-->A transition.
• Trimeric scales provide more accurate predictions of sequence-dependent conformational propensities.
• Identified specific sequence motifs (e.g., AA:TT dimers, AAN:N'TT trimers) with strong B-form preference due to groove interactions.
• The trimeric scale correlates with DNA trimer occurrences in A-form within protein-DNA complexes.

Conclusions:

• Trimeric scales offer improved prediction of DNA conformational states.
• Hydration and groove interactions play key roles in sequence-dependent B<-->A transitions.
• The developed scales can identify A-philic motifs in genomic sequences for protein-DNA recognition studies.