Click to Translate: Synthesis of Trans-Cyclooctene Modified 5' mRNA Caps for Bioorthogonal Activation.
Niclas Zips1, Ekaterina Kulko1, Stephanie Kath-Schorr1
1Department of Chemistry and Biochemistry, University of Cologne, Köln, Germany.
Chembiochem : a European Journal of Chemical Biology
|June 13, 2026
Summary
Researchers developed trans-cyclooctene (TCO)-modified mRNA caps (ZipCaps) for controlled protein expression. These ZipCaps enable reversible control of translation in cells upon tetrazine addition, offering new insights into mRNA cap structure-reactivity.
Area of Science:
- Biochemistry
- Molecular Biology
- Synthetic Chemistry
Background:
- mRNA 5'-Cap modification is a key regulator of translation.
- Limited understanding of structure-reactivity relationships in bioorthogonally activatable Cap analogues hinders precise control.
- Developing novel Cap analogues is crucial for advanced mRNA-based technologies.
Purpose of the Study:
- To synthesize and characterize trans-cyclooctene (TCO)-modified 5' mRNA caps (ZipCaps).
- To investigate the stereochemical effects of different TCO isomers on mRNA translation.
- To establish a system for reversible chemical control of protein expression in cells using ZipCaps.
Main Methods:
- Synthesis of axial and equatorial TCO-modified mRNA Cap analogues (ZipCaps).
- Comparative analysis of the stability and click-to-release reactivity of distinct TCO isomers.
- Assessment of ZipCap-modified mRNA translation efficiency in cellular systems.
- Demonstration of reversible translation control via tetrazine addition.
Main Results:
- Successfully synthesized distinct TCO isomers of ZipCaps.
- Demonstrated that stereochemistry significantly impacts ZipCap reactivity and stability.
- ZipCap-modified mRNA showed reduced translation, which was restored upon tetrazine addition.
- Observed residual translation, indicating sensitivity to Cap structure variations.
Conclusions:
- ZipCaps provide a platform for reversible, chemically induced control over mRNA translation.
- Stereochemical configuration of TCO isomers is critical for Cap analogue function.
- The findings highlight the nuanced impact of 5'-Cap modifications on Cap-dependent translation.
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