PcpA is a bacterial mononuclear non-heme Fe(II) enzyme that oxidatively cleaves 2,6-dichlorohydroquinone as a part of the pentachlorophenol degradation pathway of Sphingobium chlorophenolicum. It is structurally and mechanistically related to the much better characterized catechol extradiol dioxygenases. While there are hundreds of genes homologous to PcpA widely distributed among bacteria, virtually nothing is known about any of them. We have cloned, expressed, and purified several homologs of PcpA, and explored their possible oxidative ring-cleaving activity. Of the PcpA homologs we have expressed and purified so far, MnpC from Cupriavidus necator JMP134 and MhqO from Bacillus subtilis 168 have shown the most promise in demonstrating ring-cleaving activity with hydroquinones. Recent experiments show hydroxyhydroquinone as a possible substrate for MnpC and methylhydroquinone as a possible substrate for MhqO. These results expand the range of known hydroquinone ring-cleaving dioxygenases, and demonstrate novel differences in substrate specificity among this family of enzymes.

Cloning, expression, and characterization of novel hydroquinone ring-cleaving dioxygenases

251st National Meeting (2016)

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