Flavin-dependent halogenase (FAD-Hals) enzymes regioselectively install aromatic halogens on electron-rich substrates. This transformation ultimately gives access to compounds with increased biological activity and precursors for further synthetic derivatisation by transition-metal catalysed cross-coupling reactions. Herein, it was demonstrated that the fungal phenolic FAD-Hal RadH, from radicicol biosynthesis, is able to halogenate various bioactive scaffolds such as hydroxyisoquinolines, hydroxycoumarins and hydroxyflavonoids regioselectively. As the mechanism of these phenolic FAD-Hal enzymes remains largely unexplored, site directed mutagenesis was used to identify catalytic residues. Additionally, the evolution of a RadH mutant with enhanced expression levels and improved catalytic activity was achieved using a newly developed fluorescence-based screen. To further demonstrate the RadHâs versatility, the wild-type enzyme as well as the engineered mutant were incorporated into a biosynthetic pathway, which gave access to a novel chlorinated flavonoid non-natural product.
|Date of Award||31 Dec 2017|
- The University of Manchester
|Supervisor||Jason Micklefield (Supervisor) & David Leys (Supervisor)|