Enzymes capable of performing halogenation reactions are highly sought-after as selective and sustainable counterparts to traditional synthetic halogenation methods. The utility of halogen atoms extends to enabling complexity-generating reactions in organic synthesis as well as improving bioavailability and bioactivity in medicinal chemistry and pharmacological applications. Several classes of haloperoxidases and halogenases have been characterized and evaluated for their biocatalytic potentials, however, flavin-dependent halogenases are among the most well-studied for this application for their exceptional regioselectivities. Although significant technological advancements have been made with improving and modifying the catalytic activity of flavin-dependent halogenases to support larger scale reactions on a breadth of substrates, the majority of the enzymes studied exhibit poor turnover and limited stability. A barrier to improving catalytic efficiency has been the redox partner protein requirement to complete the flavin-dependent halogenase catalytic cycle. In recent years, a handful of unique single-component flavin-dependent halogenases have been discovered that are capable of completing a catalytic cycle without the addition of an additional redox partner protein. These self-sufficient halogenases offer an opportunity for enhanced efficiency and a simplified reaction matrix for biocatalytic halogenation. The few single-component halogenases that have been discovered share practically no sequence identity with one another and little is known about their mechanisms, substrate scopes, and catalytic cycles. The primary goals of this presented research are to understand more about the evolutionary histories of these unique halogenases, explore their substrate scopes and potential for scalable biocatalytic halogenation, and use bioinformatic tools to uncover new single-component flavin-dependent halogenases from metagenomic and metatranscriptomic datasets. The results of this study are anticipated to provide new biocatalytic tools for regioselective halogenation of aromatic compounds.

Discovery and development of single-component flavin-dependent halogenases as biocatalysts

ACS Spring 2022

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