M2*
Generation of RNA Therapeutics by Conjugating NAD-Capped RNAs to Proteins
Prof. Katharina Hoefer, Marburg University, MPI for terrestrial Microbiology; Prof. Andres Jaeschke, University of Heidelberg
Max-Planck-Innovation GmbH
Challenge
RNA-based vaccines and therapeutics are promising new tools to combat a wide range of incurable diseases and expand the range of druggable targets. Its translation into clinics, however, requires optimal RNA delivery with high RNA stability, efficient cellular internalisation and precise target affinity. Bioconjugation opened up new ways to engineer biomolecules with improved properties. However, chemical synthesis strategies to link a protein to a nucleic acid are manufacturing intensive and the non-natural bond is mostly non-hydrolysable in vivo and can cause increased cytotoxicity. Recently, the cofactor NAD was identified as a novel 5’-modification of cellular RNAs in various bacteria, archaea, eukaryotes, and viruses. The NAD modification has been shown to modulate RNA stability.
Technology
Scientists from the Max Planck Institute for Terrestrial Microbiology have discovered that NAD-capped RNAs can be covalently attached to specific target proteins by the phage T4 ADP-ribosyltransferase (ART) ModB, a process termed RNAylation. This finding reveals a distinct biological role of NAD-RNA, namely activation of RNA for enzymatic transfer and a novel way how RNAs can interact with proteins in nature. RNA-substrate and protein-target specificity of ModB have been investigated. It has been shown that ModB accepts various NAD-capped nucleic acids and attaches them covalently to defined arginine residues of proteins carrying an oligonucleotide-binding fold – called RNAylation tag.
Commercial Opportunity
- Bioconjugation: The RNAylation reaction represents a novel and sustainable conjugation method which creates a naturally occurring N-glycosidic bond with the potential to reduce immune responses and cytotoxicity in vivo compared to chemically synthesised RNA-protein conjugates.
- RNA therapeutics: The RNAylated proteins possess two functionalities derived from the nucleic acid AND the protein which (i) increase stability of the biomolecules, (ii) can change the properties of the protein due to the negatively charged RNA or by recruiting RNA-binding proteins and (iii) might allow for targeted delivery into cells to regulate cellular processes. RNAylated proteins may provide a platform to engineer the genome with high precision and represent a starting point for developing next generation.
Development Status
The platform is established at a proof of concept level. RNAylation and chemoenzymatic NAD capping have been demonstrated in vitro with multiple nucleic acid formats and protein targets, and further work towards specific therapeutic payloads and in vivo validation is ongoing/preclinical.
Patent Situation
An international patent application was filed in April, 2022: WO2023006264A1.
Further Reading
Wolfram-Schauerte, M., Pozhydaieva, N., Grawenhoff, J. et al. A viral ADP-ribosyltransferase attaches RNA chains to host proteins. Nature 620, 1054–1062 (2023). doi.org/10.1038/s41586-023-06429-2
