The Dac-tag, an affinity tag based on penicillin-binding protein 5

David Wei Lee, Mark Peggie, Maria Deak, Rachel Toth, Zoe Olivia Gage, Nicola Wood, Christina Schilde, Thimo Kurz, Axel Knebel

    Research output: Contribution to journalArticlepeer-review

    12 Citations (Scopus)


    Penicillin-binding protein 5 (PBP5), a product of the Escherichia coli gene dacA, possesses some ß-lactamase activity. On binding to penicillin or related antibiotics via an ester bond, it deacylates and destroys them functionally by opening the ß-lactam ring. This process takes several minutes. We exploited this process and showed that a fragment of PBP5 can be used as a reversible and monomeric affinity tag. At ambient temperature (e.g., 22 °C), a PBP5 fragment binds rapidly and specifically to ampicillin Sepharose. Release can be facilitated either by eluting with 10 mM ampicillin or in a ligand-free manner by incubation in the cold (1-10 °C) in the presence of 5% glycerol. The "Dac-tag", named with reference to the gene dacA, allows the isolation of remarkably pure fusion protein from a wide variety of expression systems, including (in particular) eukaryotic expression systems.
    Original languageEnglish
    Pages (from-to)64-72
    Number of pages9
    JournalAnalytical Biochemistry
    Issue number1
    Publication statusPublished - 2012


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