Lanthanide tags for site-specific ligation to an unnatural amino acid and generation of pseudocontact shifts in proteins

Choy Theng Loh, Kiyoshi Ozawa, Kellie L. Tuck, Nicholas Barlow, Thomas Huber, Gottfried Otting*, Bim Graham

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    76 Citations (Scopus)

    Abstract

    Pseudocontact shifts (PCS) from paramagnetic lanthanide ions present powerful long-range structural restraints for structural biology by NMR spectroscopy, but site-specific tagging of proteins with lanthanides remains a challenge, as most of the available lanthanide tags require proteins with single cysteine residues. We show that cyclen-based paramagnetic lanthanide tags can be attached to proteins in a site-specific manner by Cu(I)-catalyzed azide-alkyne cycloaddition to a genetically encoded p-azido-l-phenylalanine residue with a tether that proved sufficiently short and rigid for the observation of PCSs in several proteins. Despite the sterically demanding conditions associated with bulky tags and reactions close to the protein surface, ligation yields consistently above 50% and approaching 100% were obtained with the help of the Cu(I)-stabilizing ligand BTTAA. The yields were high independent of the presence of cysteine residues, thereby avoiding the need for cysteine mutations associated with conventional lanthanide-tagging strategies.

    Original languageEnglish
    Pages (from-to)260-268
    Number of pages9
    JournalBioconjugate Chemistry
    Volume24
    Issue number2
    DOIs
    Publication statusPublished - 20 Feb 2013

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