Abstract
Bifunctional catalase-peroxidases (KatGs) are heme oxidoreductases widely spread among bacteria, archaea and among lower eukaryotes. In fungi, two KatG groups with different localization have evolved, intracellular (KatG1) and extracellular (KatG2) proteins. Here, the cloning, expression analysis and subcellular localization of two novel katG1 genes from the soil fungi Chaetomium globosum and Chaetomium cochliodes are reported. Whereas, the metalloenzyme from Ch. globosum is expressed constitutively, Ch. cochliodes KatG1 reveals a slight increase in expression after induction of oxidative stress by cadmium ions and hydrogen peroxide. The intronless open reading frames of both Sordariomycetes katG1 genes as well as of almost all fungal katG1s possess two peroxisomal targeting signals (PTS1 and PTS2). Peroxisomal localization of intracellular eukaryotic catalase-peroxidases was verified by organelle separation and immunofluorescence microscopy. Co-localization with the peroxisomal enzyme 3-ketoacyl-CoA-thiolase was demonstrated for KatGs from Magnaporthe grisea, Chaetomium globosum and Chaetomium cochliodes. The physiological role of fungal catalase-peroxidases is discussed.Electronic supplementary materialThe online version of this article (doi:10.1007/s00203-013-0887-5) contains supplementary material, which is available to authorized users.
Highlights
Catalase-peroxidases represent a widespread protein family of heme b containing oxidoreductases (EC 1.11.1.21) capable of both efficientArch Microbiol (2013) 195:393–402 dismutation of hydrogen peroxide to oxygen and water as well as classical peroxidase activity with physiologically unknown endogenous electron donor(s) (Smulevich et al 2006; Zamocky et al 2008)
Co-localization with the peroxisomal enzyme 3-ketoacyl-CoA-thiolase was demonstrated for KatGs from Magnaporthe grisea, Chaetomium globosum and Chaetomium cochliodes
Phylogenetic analyses revealed that the corresponding gene was transferred during later steps of katG evolution via horizontal gene transfer (HGT) most probably from Bacteroidetes to ancestral fungal genomes (Zamocky et al 2010, 2012a)
Summary
Catalase-peroxidases (mostly abbreviated as KatGs) represent a widespread protein family of heme b containing oxidoreductases (EC 1.11.1.21) capable of both efficientArch Microbiol (2013) 195:393–402 dismutation of hydrogen peroxide to oxygen and water as well as classical peroxidase activity with physiologically unknown endogenous electron donor(s) (Smulevich et al 2006; Zamocky et al 2008). Co-localization with the peroxisomal enzyme 3-ketoacyl-CoA-thiolase was demonstrated for KatGs from Magnaporthe grisea, Chaetomium globosum and Chaetomium cochliodes. Keywords Catalase-peroxidase (KatG) · Chaetomium · Oxidative stress · Peroxisomal targeting · Thiolase · Real-time PCR
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