New Lanthanide Tag for the Generation of Pseudocontact Shifts in DNA by Site-Specific Ligation to a Phosphorothioate Group

Zuyan Wu, Michael D. Lee, Thomas J. Carruthers, Monika Szabo, Matthew L. Dennis, James D. Swarbrick*, Bim Graham, Gottfried Otting

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    20 Citations (Scopus)

    Abstract

    Pseudocontact shifts (PCS) generated by paramagnetic lanthanides provide a rich source of long-range structural restraints that can readily be measured by nuclear magnetic resonance (NMR) spectroscopy. Many different lanthanide-binding tags have been designed for site-specific tagging of proteins, but established routes for tagging DNA with a single metal ion rely on difficult chemical synthesis. Here we present a simple and practical strategy for site-specific tagging of inexpensive phosphorothioate (PT) oligonucleotides. Commercially available PT oligonucleotides are diastereomers with S and R stereoconfiguration at the backbone PT site. The respective SP and RP diastereomers can readily be separated by HPLC. A new alkylating lanthanide-binding tag, C10, was synthesized that delivered quantitative tagging yields with both diastereomers. PCSs were observed following ligation with the complementary DNA strand to form double-stranded DNA duplexes. The PCSs were larger for the SP than the RP oligonucleotide and good correlation between back-calculated and experimental PCSs was observed. The C10 tag can also be attached to cysteine residues in proteins, where it generates a stable thioether bond. Ligated to the A28C mutant of ubiquitin, the tag produced excellent fits of magnetic susceptibility anisotropy (Δχ) tensors, with larger tensors than for the tagged PT oligonucleotides, indicating that the tag is not completely immobilized after ligation with a PT group.

    Original languageEnglish
    Pages (from-to)1741-1748
    Number of pages8
    JournalBioconjugate Chemistry
    Volume28
    Issue number6
    DOIs
    Publication statusPublished - 21 Jun 2017

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