Two distinct groups of fungal catalase/peroxidases.

Catalase/peroxidases (KatGs) are bifunctional haem b-containing (Class I) peroxidases with overwhelming catalase activity and substantial peroxidase activity with various one-electron donors. These unique oxidoreductases evolved in ancestral bacteria revealing a complex gene-duplicated structure. Besides being found in numerous bacteria of all phyla, katG genes were also detected in genomes of lower eukaryotes, most prominently of sac and club fungi. Phylogenetic analysis demonstrates the occurrence of two distinct groups of fungal KatGs that differ in localization, structural and functional properties. Analysis of lateral gene transfer of bacterial katGs into fungal genomes reveals that the most probable progenitor was a katG from a bacteroidetes predecessor. The putative physiological role(s) of both fungal KatG groups is discussed with respect to known structure-function relationships in bacterial KatGs and is related with the acquisition of (phyto)pathogenicity in fungi.