Eukaryotic extracellular catalase-peroxidase from Magnaporthe grisea - Biophysical/chemical characterization of the first representative from a novel phytopathogenic KatG group

Marcel Zámocký, Enrica Droghetti, Marzia Bellei, Bernhard Gasselhuber, Martin Pabst, Paul G. Furtmüller, Gianantonio Battistuzzi, Giulietta Smulevich, Christian Obinger

Research output: Contribution to journalArticleScientificpeer-review

22 Citations (Scopus)

Abstract

All phytopathogenic fungi have two catalase-peroxidase paralogues located either intracellularly (KatG1) or extracellularly (KatG2). Here, for the first time a secreted bifunctional, homodimeric catalase-peroxidase (KatG2 from the rice blast fungus Magnaporthe grisea) has been produced heterologously with almost 100% heme occupancy and comprehensively investigated by using a broad set of methods including UV-Vis, ECD and resonance Raman spectroscopy (RR), thin-layer spectroelectrochemistry, mass spectrometry, steady-state & presteady-state spectroscopy. RR spectroscopy reveals that MagKatG2 shows a unique mixed-spin state, non-planar heme b, and a proximal histidine with pronounced imidazolate character. At pH 7.0 and 25 °C, the standard reduction potential E°′ of the Fe(III)/Fe(II) couple for the high-spin native protein was found to fall in the range typical for the KatG family. Binding of cyanide was relatively slow at pH 7.0 and 25 °C and with a K d value significantly higher than for the intracellular counterpart. Demonstrated by mass spectrometry MagKatG2 has the typical Trp118-Tyr251-Met277 adduct that is essential for its predominantly catalase activity at the unique acidic pH optimum. In addition, MagKatG2 acts as a versatile peroxidase using both one- and two-electron donors. Based on these data, structure-function relationships of extracellular eukaryotic KatGs are discussed with respect to intracellular KatGs and possible role(s) in host-pathogen interaction.

Original languageEnglish
Pages (from-to)673-683
JournalBiochimie
Volume94
Issue number3
DOIs
Publication statusPublished - 2012
Externally publishedYes

Keywords

  • Extracellular catalase-peroxidase
  • Oxidative stress
  • Peroxidases-catalase superfamily
  • Phytopathogen
  • Reduction potential
  • Resonance Raman spectroscopy

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