Identification and Characterization of the Haloperoxidase VPO-RR from Rhodoplanes roseus by Genome Mining and Structure-Based Catalytic Site Mapping

Halogenating enzymes have evolved in considerable mechanistic diversity. The apparent need for secondary metabolism coincides with the current need to introduce halogens in synthetic products. The potential of halogenating enzymes and, especially, vanadate-dependent haloperoxidases has been insufficiently exploited for synthetic purposes. In this work, we identified potential halogenase sequences by screening algal, fungal, and protobacterial sequence databases, structural modeling of putative halogenases, and mapping and comparing active sites. In a final step, individual haloperoxidases were expressed and kinetically characterized. A vanadate-dependent haloperoxidase from Rhodoplanes roseus was heterologously expressible by E. coli and could be purified to homogeneity. The kinetic data revealed a higher turnover number than the known VClPO-CI and no inhibitory effect from bromide, rendering this enzyme a promising biocatalyst. Other predicted haloperoxidases were not expressed successfully yet but these enzymes were predicted to be present in a wide taxonomic variety.