Crystal Structures of a Poplar Thioredoxin Peroxidase that Exhibits the Structure of Glutathione Peroxidases: Insights into Redox-driven Conformational Changes

Cha San Koh, Claude Didierjean, Nicolas Navrot, Santosh Panjikar, Guillermo Mulliert, Nicolas Rouhier, Jean Pierre Jacquot, André Aubry, Omar Shawkataly, Catherine Corbier

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70 Citations (Scopus)

Abstract

Glutathione peroxidases (GPXs) are a group of enzymes that regulate the levels of reactive oxygen species in cells and tissues, and protect them against oxidative damage. Contrary to most of their counterparts in animal cells, the higher plant GPX homologues identified so far possess cysteine instead of selenocysteine in their active site. Interestingly, the plant GPXs are not dependent on glutathione but rather on thioredoxin as their in vitro electron donor. We have determined the crystal structures of the reduced and oxidized form of Populus trichocarpa × deltoides GPX5 (PtGPX5), using a selenomethionine derivative. PtGPX5 exhibits an overall structure similar to that of the known animal GPXs. PtGPX5 crystallized in the assumed physiological dimeric form, displaying a pseudo ten-stranded β sheet core. Comparison of both redox structures indicates that a drastic conformational change is necessary to bring the two distant cysteine residues together to form an intramolecular disulfide bond. In addition, a computer model of a complex of PtGPX5 and its in vitro recycling partner thioredoxin h1 is proposed on the basis of the crystal packing of the oxidized form enzyme. A possible role of PtGPX5 as a heavy-metal sink is also discussed.

Original languageEnglish
Pages (from-to)512-529
Number of pages18
JournalJournal of Molecular Biology
Volume370
Issue number3
DOIs
Publication statusPublished - 13 Jul 2007
Externally publishedYes

Keywords

  • glutathione peroxidase
  • Molecular Dynamics
  • redox state
  • thioredoxin peroxidase
  • X-ray structure

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