Highly Specific Recognition of Guanosine Using Engineered Base-Excised Aptamers

Area of Science:

• Molecular Biology
• Biochemistry
• Biotechnology

Background:

• Purines are crucial biological molecules involved in nucleic acid synthesis, energy storage, and signaling.
• Developing DNA aptamers for specific guanosine binding has been challenging, unlike for adenine derivatives.

Purpose of the Study:

• To engineer existing DNA aptamers for specific guanosine recognition using a novel base-excision strategy.
• To create guanosine-binding aptamers without employing traditional SELEX (Systematic Evolution of Ligands by Exponential Enrichment) methods.

Main Methods:

• A base-excision strategy was applied to manipulate existing DNA aptamers, including a Na+ -binding aptamer and an adenosine aptamer.
• Seven guanosine aptamers were engineered by excising specific bases from the selected aptamer scaffolds.
• The binding specificity and affinity of the engineered aptamers for guanosine were systematically evaluated.

Main Results:

• The G16-deleted Na+ aptamer demonstrated the highest specificity and affinity for guanosine, with an apparent dissociation constant (Kd) of 0.78 mM.
• The engineered aptamers could distinguish target molecules with single monophosphate differences.
• The study confirmed the generality of both the aptamer scaffold and the excised site for engineering purposes.

Conclusions:

• A non-SELEX method, base-excision, successfully generated functional guanosine-binding DNA aptamers.
• This approach provides a valuable alternative for developing aptamers against challenging targets like guanosine.
• The findings offer deeper insights into the engineering of aptamers for enhanced molecular recognition capabilities.