Interactions of in vitro selected fluorogenic peptide aptamers with calmodulin

Area of Science:

• Biochemistry
• Molecular Biology
• Biotechnology

Background:

• Aptamers are nucleic acid or peptide molecules that bind to a specific target molecule.
• Calmodulin (CaM) is a calcium-binding protein involved in many cellular processes.
• Previous aptamer selection methods may not fully optimize binding conditions.

Purpose of the Study:

• To investigate the impact of selection conditions on aptamer performance.
• To evaluate the binding affinity and selectivity of modified aptamers for CaM.
• To understand the structural basis of enhanced aptamer-target interactions.

Main Methods:

• Ribosome display for aptamer selection.
• Modification of aptamer sequences by adding N-terminal residues.
• Surface plasmon resonance (SPR) and fluorescence spectroscopy for binding analysis.
• Nuclear magnetic resonance (NMR) spectroscopy for structural determination.

Main Results:

• Addition of N-terminal residues to a previously selected aptamer drastically improved its binding affinity and selectivity for CaM.
• SPR and fluorescence data confirmed enhanced binding characteristics.
• NMR analysis revealed that the primary binding site is at the C-terminal of CaM, with additional residues enhancing interactions.

Conclusions:

• Aptamer selection conditions significantly influence binding efficacy.
• Optimizing aptamer sequences with elements used during selection can lead to superior binding performance.
• This study highlights the importance of considering the entire aptamer sequence, including selection tags, for optimal target engagement.