Affinity protein-oligonucleotide conjugates combine the targeting abilities of affinity proteins and properties of nucleic acids and can act as highly efficient biosensors in a range of diagnostic and therapeutic assays. Although the application of affinity protein-oligonucleotide conjugates has increased steadily since their introduction, the techniques used to produce them have remained largely unchanged. Additionally, few studies have evaluated the comparative impact of conjugation strategy on the effectiveness of the resulting affinity protein-oligonucleotide. Andres Rocha Tapia and colleagues from the deMello group, KTH Royal Institute of Technology and University College London have proposed a new powerful technique for selectively attaching affinity proteins to oligonucleotides at user-defined sites. Significant, this new method operates at high yield (93%) and on short timescales (15 minutes).
The team used surface plasmon resonance (SPR) to investigate the influence of affinity protein selection, conjugation strategy, and DNA length on target binding, with findings highlighting the harmful consequences of non-specific conjugation methods. Specifically, the team created an affinity protein-oligonucleotide conjugate library by combining non-selective and site-selective chemistries using IgG and non-IgG ligands, with SPR being used to report target binding profiles. Various methods for testing affinity protein-oligonucleotide conjugates, including plate-based immuno-PCR assays and cell-surface receptor imaging were then assessed. Importantly, results highlighted the significance of site-selective conjugation strategies, which require precise design and construction of affinity protein-DNA conjugates, with specific reactions being required to create smaller proteins with high affinity. To cut a long story short, it is crucial to be extremely careful when choosing where to attach the proteins and the length of the DNA cargo.
Written by Rashin Mohammadi
The full paper can be read here.