Structural changes caused by radiation-induced reduction and radiolysis: the effect of X-ray absorbed dose in a fungal multicopper oxidase

Eugenio De la Mora, Janet E. Lovett, Christopher F. Blanford, Elspeth F. Garman, Brenda Valderrama, Enrique Rudino-Pinera*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

47 Citations (Scopus)

Abstract

X-ray radiation induces two main effects at metal centres contained in protein crystals: radiation-induced reduction and radiolysis and a resulting decrease in metal occupancy. In blue multicopper oxidases (BMCOs), the geometry of the active centres and the metal-to-ligand distances change depending on the oxidation states of the Cu atoms, suggesting that these alterations are catalytically relevant to the binding, activation and reduction of O2. In this work, the X-ray-determined three-dimensional structure of laccase from the basidiomycete Coriolopsis gallica (Cg L), a high catalytic potential BMCO, is described. By combining spectroscopic techniques (UVVis, EPR and XAS) and X-ray crystallography, structural changes at and around the active copper centres were related to pH and absorbed X-ray dose (energy deposited per unit mass). Depletion of two of the four active Cu atoms as well as low occupancies of the remaining Cu atoms, together with different conformations of the metal centres, were observed at both acidic pH and high absorbed dose, correlating with more reduced states of the active coppers. These observations provide additional evidence to support the role of flexibility of copper sites during O2 reduction. This study supports previous observations indicating that interpretations regarding redox state and metal coordination need to take radiation effects explicitly into account.

Original languageEnglish
Pages (from-to)564-577
Number of pages14
JournalActa Crystallographica. Section D, Biological crystallography
Volume68
DOIs
Publication statusPublished - May 2012

Keywords

  • bioelectrocatalysis
  • blue multicopper oxidases
  • copper reduction
  • dioxygen
  • fungal laccases
  • MicroPIXE
  • O2 reduction
  • protein electrochemistry
  • radiolysis
  • radiation damage
  • X-ray-induced reduction
  • MELANOCARPUS-ALBOMYCES LACCASE
  • BLUE COPPER PROTEINS
  • RHUS-VERNICIFERA LACCASE
  • CRYSTAL-STRUCTURE
  • MACROMOLECULAR CRYSTALS
  • ANGSTROM RESOLUTION
  • SYNCHROTRON-RADIATION
  • DIOXYGEN REDUCTION
  • COPRINUS-CINEREUS
  • ASCORBATE OXIDASE

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