Combinatorial Design of a Nanobody that Specifically Targets Structured RNAs

Area of Science:

• Molecular Biology
• Structural Biology
• Biochemistry

Background:

• The human genome contains a vast number of functional non-coding RNAs, many with crucial 3D structures.
• Understanding structured RNA (stRNA) function is vital, but RNA crystallization remains a significant challenge.
• Existing methods for studying stRNAs are limited, hindering research into their cellular roles.

Purpose of the Study:

• To develop a versatile tool for studying and crystallizing structured RNAs (stRNAs).
• To engineer a nanobody capable of specifically recognizing and binding to stRNAs.

Main Methods:

• Antibody engineering using camelid heavy-chain variable fragments (nanobodies).
• Affinity testing using techniques like surface plasmon resonance (SPR) to measure binding kinetics.
• Characterization of nanobody binding specificity against various nucleic acids and proteins.
• Assessment of nanobody impact on stRNA secondary structure and thermal stability.

Main Results:

• Engineered a nanobody with low nanomolar affinity for stRNAs.
• Demonstrated specific binding to stRNAs, with no detectable binding to single-stranded DNA/RNA, double-stranded DNA/RNA, or a negatively charged protein.
• Identified a shared epitope recognized by the nanobody across different stRNAs.
• Confirmed that nanobody binding does not alter stRNA secondary structure or thermal unfolding/refolding properties.

Conclusions:

• Nanobodies can be successfully engineered to recognize specific RNA structural epitopes.
• This novel nanobody serves as a promising tool for advancing stRNA research, including structural studies and crystallization efforts.
• The findings open new avenues for exploring the functions and mechanisms of non-coding RNAs.