A widely distributed metalloenzyme class enables gut microbial metabolism of host- and diet-derived catechols

Catechol dehydroxylation is a central chemical transformation in the gut microbial metabolism of plant- and host-derived small molecules. However, the molecular basis for this transformation and its distribution among gut microorganisms are poorly understood. Here, we characterize a molybdenum-dependent enzyme from the prevalent human gut bacterium Eggerthella lenta that specifically dehydroxylates catecholamine neurotransmitters available in the human gut. Our findings suggest that this activity enables E. lenta to use dopamine as an electron acceptor under anaerobic conditions. In addition to characterizing catecholamine dehydroxylation, we identify candidate molybdenum-dependent enzymes that dehydroxylate additional host-and plant-derived small molecules. These gut bacterial catechol dehydroxylases are specific in their substrate scope and transcriptional regulation and belong to a distinct group of largely uncharacterized molybdenum-dependent enzymes that likely mediate both primary and secondary metabolism in multiple environments. Finally, we observe catechol dehydroxylation in the gut microbiotas of diverse mammals, suggesting that this chemistry is present in habitats beyond the human gut. Altogether, our data reveal the molecular basis of catechol dehydroxylation among gut bacteria and suggest that the chemical strategies that mediate metabolism and interactions in the human gut are relevant to a broad range of species and habitats.