Reaction pathway engineering converts a radical hydroxylase into a halogenase.
Neugebauer, M.E., Kissman, E.N., Marchand, J.A., Pelton, J.G., Sambold, N.A., Millar, D.C., Chang, M.C.Y.(2022) Nat Chem Biol 18: 171-179
- PubMed: 34937913 
- DOI: https://doi.org/10.1038/s41589-021-00944-x
- Primary Citation of Related Structures:  
7JSD - PubMed Abstract: 
Fe II /α-ketoglutarate (Fe II /αKG)-dependent enzymes offer a promising biocatalytic platform for halogenation chemistry owing to their ability to functionalize unactivated C-H bonds. However, relatively few radical halogenases have been identified to date, limiting their synthetic utility. Here, we report a strategy to expand the palette of enzymatic halogenation by engineering a reaction pathway rather than substrate selectivity. This approach could allow us to tap the broader class of Fe II /αKG-dependent hydroxylases as catalysts by their conversion to halogenases. Toward this goal, we discovered active halogenases from a DNA shuffle library generated from a halogenase-hydroxylase pair using a high-throughput in vivo fluorescent screen coupled to an alkyne-producing biosynthetic pathway. Insights from sequencing halogenation-active variants along with the crystal structure of the hydroxylase enabled engineering of a hydroxylase to perform halogenation with comparable activity and higher selectivity than the wild-type halogenase, showcasing the potential of harnessing hydroxylases for biocatalytic halogenation.
Organizational Affiliation: 
Department of Chemical & Biomolecular Engineering, University of California, Berkeley, Berkeley, CA, USA.