Discovery of Novel Bacterial Chalcone Isomerases by a Sequence‐Structure‐Function‐Evolution Strategy for Enzymatic Synthesis of (<i>S</i>)‐Flavanones
Hannes Meinert, Dong Yi, Bastian Zirpel, Eva Schuiten, Torsten Geißler, Egon Gross, Stephan Brückner, Beate Hartmann, Carsten Röttger, Jakob P. Ley, Uwe T. Bornscheuer
Abstract
Abstract Chalcone isomerase (CHI) is a key enzyme in the biosynthesis of flavonoids in plants. The first bacterial CHI (CHI era ) was identified from Eubacterium ramulus, but its distribution, evolutionary source, substrate scope, and stereoselectivity are still unclear. Here, we describe the identification of 66 novel bacterial CHIs from Genbank using a novel Sequence‐Structure‐Function‐Evolution (SSFE) strategy. These novel bacterial CHIs show diversity in substrate specificity towards various hydroxylated and methoxylated chalcones. The mutagenesis of CHI era according to the substrate binding models of these novel bacterial CHIs resulted in several variants with greatly improved activity towards these chalcones. Furthermore, the preparative scale conversion catalyzed by bacterial CHIs has been performed for five chalcones and revealed ( S )‐selectivity with up to 96 % ee, which provides an alternative biocatalytic route for the synthesis of ( S )‐flavanones in high yields.