Nucleotide rigidity

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• Nucleoside and nucleotide conformations are crucial for nucleic acid structure and function.
• Previous studies suggested nucleotides might be more rigid than nucleosides.

Purpose of the Study:

• To investigate the backbone flexibility of adenosine and related nucleotides in aqueous solution.
• To determine if nucleotide flexibility is conserved in polynucleotides and under different base-pairing conditions.
• To extend these findings to other nucleoside systems and predict conformations in yeast tRNA.

Main Methods:

• Conformational analysis in aqueous solution.
• Comparison of nucleoside and nucleotide flexibility.
• Examination of polynucleotide (ApA, ApApA, poly(A)) conformations.
• Extrapolation to yeast tRNA structure.

Main Results:

• Adenosine, 3'-AMP, 5'-AMP, and 3',5'-ADP show comparable backbone flexibility in solution.
• Nucleotide flexibility is conserved in destacked ApA, ApApA, and poly(A) but not in base-stacked regions.
• Similar flexibility patterns were observed for guanosine, uridine, and cytidine systems.
• Yeast tRNA conformations are predicted to be stable in stacked regions and flexible in unstacked regions.

Conclusions:

• Nucleotides are not inherently more rigid than nucleosides in aqueous solution.
• Base stacking significantly restricts nucleotide flexibility, while unstacked regions retain flexibility.
• This conformational flexibility is a key feature of nucleic acid structure, particularly in regions like the D-loop and A-loop of tRNA.