Rational Design of a DNA-Scaffolded High-Affinity Binder for Langerin.

Gunnar Bachem,Oliver Seitz,Jens Dernedde,Kim Silberreis,Felix Fuchsberger,Hannes Baukmann,Eike‐Christian Wamhoff,Christoph Rademacher,Dongyoon Kim

doi:10.1002/anie.202006880

Abstract

Binders of langerin could target vaccines to Langerhans cells for improved therapeutic effect. Since langerin has low affinity for monovalent glycan ligands, highly multivalent presentation has previously been key for targeting. Aiming to reduce the amount of ligand required, we rationally designed molecularly defined high‐affinity binders based on the precise display of glycomimetic ligands (Glc2NTs) on DNA‐PNA scaffolds. Rather than mimicking langerin's homotrimeric structure with a C3‐symmetric scaffold, we developed readily accessible, easy‐to‐design bivalent binders. The method considers the requirements for bridging sugar binding sites and statistical rebinding as a means to both strengthen the interactions at single binding sites and amplify the avidity enhancement provided by chelation. This gave a 1150‐fold net improvement over the affinity of the free ligand and provided a nanomolar binder (IC50=300 nM) for specific internalization by langerin‐expressing cells.

Highlights

Carbohydrate-protein interactions drive important biological recognition processes on cell membranes
Chemie affected by the linkers used by us.[13b,15d–i,16] due to the rigidity of DNA scaffolds statistical rebinding cannot contribute to the multivalent interactions if ligands are separated by large distances
The langerin extracellular domain (ECD) forms a trimeric structure comprised of three carbohydrate recognitions domains (CRD).[20]

Summary

Introduction

Chemie affected by the linkers used by us (meaning that highest affinities were obtained for complexes presenting the ligands in a distance that matched the distance between binding sites on structurally characterized targets).[13b,15d–i,16] due to the rigidity of DNA scaffolds statistical rebinding cannot contribute to the multivalent interactions if ligands are separated by large distances. Three-arm DNA scaffolds have been optimized for interactions with receptors offering three binding sites.[18] Such distance-matched multivalent scaffolds are difficult to design and often the affinity enhancements remain in the order expected for bivalent interactions. The langerin extracellular domain (ECD) forms a trimeric structure comprised of three carbohydrate recognitions domains (CRD).[20] Rather than attempting the design of a C3-symmetrical scaffold that would match the arrangement of langerins sugar binding sites, we present a straightforward method to enhance the avidity of readily accessible, easy to design bivalent binders. In this first systematic study, we use statistical rebinding to improve interactions at individual sugar binding sites and amplify the x-fold chelate bivalency enhancement

Results and Disucssion

Conclusion

Conflict of interest