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

15 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

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


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