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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