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The spatial alignment of functional groups is a central aspect of most catalytic processes. Protein scaffolds with their exceptional molecular recognition properties have evolved into powerful biological catalysts. However, the rational design of artificial enzymes starting from non-catalytic protein domains proved challenging. Herein, we report the use of a non-enzymatic protein as template for amide bond formation. Starting from a protein adaptor domain capable of simultaneously binding to two peptide ligands, we designed a catalytic transfer reaction based on the native chemical ligation. This system was used for the selective labelling of a target protein validating its high chemoselectivity and potential as a novel tool for the selective covalent modification of proteins.

Ligand-directed reactions allow chemical transformations at very low reactant concentrations and can thus provide access to efficient approaches for the post-translational modification of proteins. The development of these proximity-induced reactions is hampered by the number of appropriate ligands and the lack of design principles. Addressing these limitations, we report a proximity-induced labeling system which applies a moderate affinity peptide ligand. The design process was structure-guided and supported by molecular dynamics simulations. We show that selective protein labeling can be performed inside living cells enabling the subcellular translocation of a protein via ligand-directed chemistry for the first time.

Molekulare Template binden spezifisch Reaktanten und erhohen somit deren effektive Konzentration, was zur Beschleunigung von chemischen Reaktionen fuhren kann. Dieses Konzept wurde bereits erfolgreich auf einige Fragestellungen vor allem aus dem Bereich der Nukleinsaure-vermittelten Chemie angewendet. Wir prasentieren die erste Protein-vermittelte Reaktion, welche die N-terminale Verknupfung zweier Peptide ermoglicht. In Anwesenheit des Proteintemplats wurde die Verknupfungsreaktion um mehr als drei Grosenordnungen beschleunigt. Die Templat-vermittelten Reaktionen verlaufen hochselektiv und wurden erfolgreich fur die kovalente Markierung eines Zielproteins direkt im Zelllysat verwendet.

Molecular templates bind particular reactants, thereby increasing their effective concentrations and accelerating the corresponding reaction. This concept has been successfully applied to a number of chemical problems with a strong focus on nucleic acid templated reactions. We present the first protein-templated reaction that allows N-terminal linkage of two peptides. In the presence of a protein template, ligation reactions were accelerated by more than three orders of magnitude. The templated reaction is highly selective and proved its robustness in a protein-labeling reaction that was performed in crude cell lysate.