X-ray Crystal Structure of Divalent Metal-Activated β-xylosidase, RS223BX

Douglas B. Jordan*, Jay D. Braker, Kurt Wagschal, Charles C. Lee, Victor J. Chan, Ievgeniia Dubrovska, Spencer M Anderson, Zdzislaw Wawrzak

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    12 Scopus citations


    We report the X-ray crystal structure of a glycoside hydrolase family 43 β-xylosidase, RS223BX, which is strongly activated by the addition of divalent metal cations. The 2.69 Å structure reveals that the Ca2+ cation is located at the back of the active-site pocket. The Ca2+ is held in the active site by the carboxylate of D85, an “extra” acid residue in comparison to other GH43 active sites. The Ca2+ is in close contact with a histidine imidazole, which in turn is in contact with the catalytic base (D15) thus providing a mechanism for stabilizing the carboxylate anion of the base and achieve metal activation. The active-site pocket is mirrored by an “inactive-site” pocket of unknown function that resides on the opposite side of the monomer.

    Original languageEnglish (US)
    Pages (from-to)637-648
    Number of pages12
    JournalApplied Biochemistry and Biotechnology
    Issue number3
    StatePublished - Oct 30 2015


    • Activation
    • Divalent metal cations
    • GH43 β-xylosidase
    • Inverting mechanism

    ASJC Scopus subject areas

    • Biotechnology
    • Bioengineering
    • Biochemistry
    • Applied Microbiology and Biotechnology
    • Molecular Biology


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