Identification and functional analysis of peroxiredoxin isoforms in Euglena gracilis

Biosci Biotechnol Biochem. 2014;78(4):593-601. doi: 10.1080/09168451.2014.890037. Epub 2014 May 21.


Euglena gracilis lacks catalase and contains ascorbate peroxidase (APX) which is localized exclusively in the cytosol. Other enzymes that scavenge reactive oxygen species (ROS) in Euglena have not yet been identified; therefore, ROS metabolism, especially in organelles, remains unclear in Euglena. The full-length cDNAs of four Euglena peroxiredoxins (EgPrxs) were isolated in this study. EgPrx1 and -4 were predicted to be localized in the cytosol, and EgPrx2 and -3 in plastids and mitochondria, respectively. The catalytic efficiencies of recombinant EgPrxs were similar to those of plant thiol-peroxidases, but were markedly lower than those of APX from Euglena. However, transcript levels of EgPrx1, -2, and -3 were markedly higher than those of APX. The growth rate of Euglena cells, in which the expression of EgPrx1 and -4 was suppressed by gene silencing, was markedly reduced under normal conditions, indicating physiological significance of Prx proteins.

Keywords: Euglena gracilis; peroxiredoxin; reactive oxygen species.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cell Proliferation
  • Euglena gracilis / cytology
  • Euglena gracilis / enzymology*
  • Euglena gracilis / genetics
  • Gene Knockdown Techniques
  • Hydrogen Peroxide / metabolism
  • Isoenzymes / chemistry
  • Isoenzymes / deficiency
  • Isoenzymes / genetics
  • Isoenzymes / metabolism
  • Molecular Sequence Data
  • Peroxiredoxins / chemistry
  • Peroxiredoxins / deficiency
  • Peroxiredoxins / genetics
  • Peroxiredoxins / metabolism*


  • Isoenzymes
  • Hydrogen Peroxide
  • Peroxiredoxins