Mutant ATP-binding RNA aptamers reveal the structural basis for ligand binding

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• The three-dimensional structure of the ATP-binding RNA aptamer is crucial for its function.
• Understanding the interactions that stabilize the aptamer and confer specificity is essential for its application.
• Previous studies have focused on the overall fold, but the role of specific conserved nucleotides was less clear.

Purpose of the Study:

• To investigate the structural and functional roles of conserved nucleotides within the ATP-binding RNA aptamer.
• To explore how mutations and ligand modifications affect aptamer binding properties.
• To gain deeper insights into the hydrogen bond network governing aptamer stability and ATP specificity.

Main Methods:

• Nuclear Magnetic Resonance (NMR) spectroscopy for solution structure determination and binding studies.
• Column binding assays to quantify aptamer-ligand interactions.
• Molecular modeling to visualize and analyze molecular interactions.

Main Results:

• The solution structure of the ATP-binding RNA aptamer was determined, highlighting the importance of stacking and hydrogen bond interactions.
• Highly conserved nucleotides in the ATP binding pocket were found to be substitutable while maintaining binding affinity.
• Mutant aptamers and modified ligands exhibited altered binding properties, providing evidence for specific interaction networks.

Conclusions:

• The study reveals a surprising degree of flexibility in conserved nucleotide positions within the ATP-binding aptamer.
• Hydrogen bonding networks play a critical role in defining the aptamer's structure, stability, and specificity for ATP.
• These findings advance the understanding of aptamer-ligand recognition and have implications for aptamer design and engineering.