Folding versus charge: understanding selective target recognition by the thrombin aptamers.

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Discovery

Background:

• Nucleic acids, including DNA and RNA, are increasingly utilized as therapeutic agents.
• Oligonucleotide aptamers are short nucleic acid sequences with high specificity and affinity for target molecules, comparable to antibodies.
• The structural flexibility of nucleic acids allows for diverse folding patterns, crucial for aptamer function.

Purpose of the Study:

• To investigate the contributions of aptamer folding, sequence, and charge interactions in target recognition.
• To compare the binding and inhibition properties of the Thrombin aptamer (TBA) with unrelated oligonucleotides.
• To assess differences in protein exosite recognition using aptamers targeting distinct thrombin binding sites.

Main Methods:

• Selection and characterization of DNA aptamers, including the 15-mer Thrombin aptamer (15fTBA) and the 29-mer 29hTBA.
• Comparative analysis of aptamer-protein complex formation and stability.
• Evaluation of aptamer-mediated inhibition of protein activity.

Main Results:

• The formation of stable protein-DNA complexes is influenced by both sequence/folding complementarities and electrostatic interactions.
• Thrombin aptamer (TBA) exhibits specific binding and inhibition properties for thrombin's exosite I.
• Aptamer folding and sequence, in conjunction with charge density, are critical for selective recognition of distinct protein exosites (I and II).

Conclusions:

• A subtle interplay between aptamer folding, sequence, and charge density governs the selective and effective recognition of protein targets.
• Oligonucleotide aptamers demonstrate significant potential as targeted therapeutics by exploiting these molecular recognition principles.
• Understanding these interactions is key to designing novel aptamer-based drugs with enhanced efficacy and specificity.