Graphene Biosensor Differentiating Sensitive Interactions between Ribonucleic Acid and Dipeptide Repeats in...

Area of Science:

• Biophysics
• Neuroscience
• Materials Science

Background:

• Liquid-Liquid Phase Separation (LLPS) is vital in cell biology and implicated in neurodegenerative diseases such as ALS and FTD.
• Mutations in C9ORF72 gene produce arginine-rich dipeptide repeat proteins (R-DPRs) that disrupt LLPS and contribute to disease pathology.
• Existing methods struggle to detect weak intermolecular interactions within LLPS droplets.

Purpose of the Study:

• To utilize graphene field-effect transistors (GFETs) for sensitive detection of molecular interactions in LLPS.
• To investigate the interaction mechanisms between R-DPRs and RNA.
• To explore the role of peptide properties, like proline-induced rigidity, in LLPS.

Main Methods:

• Immobilization of RNA (poly-A) onto GFETs.
• Measurement of GFET electrical conductivity to detect shifts in the charge neutral point.
• Characterization of interactions with dipeptide repeat peptides (poly(PR), poly(GR), R12) at varying concentrations.

Main Results:

• GFETs detected peptide-RNA interactions at nanomolar concentrations, significantly improving sensitivity over traditional methods.
• Interactions were dependent on peptide concentration and varied between different peptide types.
• Peptides with proline residues showed nonuniform spatial distribution, indicating proline-induced rigidity influences RNA interactions.

Conclusions:

• GFETs offer a highly sensitive platform for studying molecular interactions relevant to LLPS and neurodegenerative diseases.
• Peptide rigidity, particularly from proline residues, plays a key role in multivalent interactions with RNA.
• This research provides new insights into the mechanisms of R-DPRs in LLPS and disease pathogenesis.