Radical formation on a conserved tyrosine residue is crucial for DyP activity

•We identified a tyrosine as a substrate interaction site of a DyP-type peroxidase.•Spin-trapping revealed a radical intermediate at Tyr337.•The catalytically active Tyr is strictly conserved among fungal DyPs, EfeB and TyrA.•The proposed LRET pathway from Tyr337 to the heme is conserved in fungal DyPs.•Substrate specificity can be linked to the exposure of the catalytically active Tyr.

Dye-decolorizing peroxidases (DyPs) are able to cleave bulky anthraquinone dyes. The recently published crystal structure of AauDyPI reveals that a direct oxidation in the distal heme cavity can be excluded for most DyP substrates. It is shown that a surface-exposed tyrosine residue acts as a substrate interaction site for bulky substrates. This amino acid is conserved in eucaryotic DyPs but is missing in the structurally related chlorite dismutases (Clds). Dye-decolorizing peroxidases of procaryotic origin equally possess a conserved tyrosine in the same region of the polypeptide albeit not at the homologous position.

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