Base dependence of B-DNA sugar conformation in solution and in the solid state

Area of Science:

• Molecular Biology
• Structural Biology
• Biophysics

Background:

• Deoxyribose sugar conformation is a key determinant of DNA structure and function.
• Previous studies have explored DNA sugar pucker, but base-specific conformational differences remain an area of investigation.

Purpose of the Study:

• To investigate and elucidate the differences in deoxyribose sugar conformation between purine and pyrimidine nucleotides in DNA duplexes.
• To correlate solution-state Nuclear Overhauser Effect Spectroscopy (NOESY) data with crystallographic findings for DNA.

Main Methods:

• Analysis of 1H-NOESY data from eight short DNA duplexes in solution.
• Comparison of experimental data with high-resolution B-DNA crystal structures and model sugar conformations.
• Calculation of J-coupling constants based on B-type DNA crystal structures.

Main Results:

• Significant differences in sugar conformation were observed between purine and pyrimidine nucleotides.
• Pyrimidine sugars exhibited a shorter H1'-H4' interproton distance (< 3.0 Å) and smaller pseudorotation phase angles (P: 90°–150°).
• Purine sugars showed a longer H1'-H4' interproton distance (> 3.0 Å) and larger pseudorotation phase angles (P: 140°–180°), indicating a general C2'-endo conformation for deoxyribose.

Conclusions:

• Deoxyribose sugar conformation in DNA exhibits base-specific characteristics, particularly in solution.
• The observed differences in pseudorotation parameters provide insights into the conformational flexibility of DNA.
• Experimental coupling measurements show potential for determining DNA sugar conformation.