Flavin-mediated dual oxidation controls an enzymatic Favorskii-type rearrangement.
Teufel, R., Miyanaga, A., Michaudel, Q., Stull, F., Louie, G., Noel, J.P., Baran, P.S., Palfey, B., Moore, B.S.(2013) Nature 503: 552-556
- PubMed: 24162851 
- DOI: https://doi.org/10.1038/nature12643
- Primary Citation of Related Structures:  
3W8W, 3W8X, 3W8Z, 4XLO - PubMed Abstract: 
Flavoproteins catalyse a diversity of fundamental redox reactions and are one of the most studied enzyme families. As monooxygenases, they are universally thought to control oxygenation by means of a peroxyflavin species that transfers a single atom of molecular oxygen to an organic substrate. Here we report that the bacterial flavoenzyme EncM catalyses the peroxyflavin-independent oxygenation-dehydrogenation dual oxidation of a highly reactive poly(β-carbonyl). The crystal structure of EncM with bound substrate mimics and isotope labelling studies reveal previously unknown flavin redox biochemistry. We show that EncM maintains an unexpected stable flavin-oxygenating species, proposed to be a flavin-N5-oxide, to promote substrate oxidation and trigger a rare Favorskii-type rearrangement that is central to the biosynthesis of the antibiotic enterocin. This work provides new insight into the fine-tuning of the flavin cofactor in offsetting the innate reactivity of a polyketide substrate to direct its efficient electrocyclization.
Organizational Affiliation: 
Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, 92093, USA.