Discovery of Novel Bacterial Chalcone Isomerases by a Sequence‐Structure‐Function‐Evolution Strategy for Enzymatic Synthesis of (S)‐Flavanones

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.Nature produces an enormous variety of biomolecules, among which flavonoids are a large class of secondary metabolites mainly derived from plants. Flavonoids have many functions in plants, such as flower coloration, UV filtration, symbiotic nitrogen fixation, and floral pigmentation. In addition, they also act as chemical messengers, physiological regulators, cell cycle inhibitors, and antibiotics against plant diseases. [1] In our long history of using medicinal[*] B.

Discovery of a Unique Flavonoid Biosynthesis Mechanism in Fungi by Genome Mining

“…Plant CHIs share high sequence identities and 3D structural similarities with each other, and catalyze the irreversible isomerization of chalcone into flavanones using a catalytic H 2 O‐mediated acid‐base mechanism due to the solvent‐exposed substrate‐binding site during the catalytic process (Figure S15a) [16] . Bacterial CHIs also share high sequence identities with each other, and catalyze the reversible reactions from flavanones to chalcones [17] . The physiological role of bacterial CHI is to participate in the degradation of flavanone in gut bacteria (Figure S15b,c) [18, 19] .…”

“…[16] Bacterial CHIs also share high sequence identities with each other, and catalyze the reversible reactions from flavanones to chalcones. [17] The physiological role of bacterial CHI is to participate in the degradation of flavanone in gut bacteria (Figure S15b,c). [18,19] The sequence identities between CfoK and plant CHIs are only 9.8-13.1 %, and those between CfoK and bacterial CHIs are 6.7-10.8 % (Figure S16).…”

The green chemistry of chalcones: Valuable sources of privileged core structures for drug discovery

“…Through the Sequence-Structure-Function-Evolution (SSFE) strategy the research group of Meinert and coworkers discovered 66 novel bacterial chalcone isomerase enzymes (CHIs) using the GenBank database. These enzymes have been investigated because they can be used as a sustainable synthetic route to obtain ( S )-flavones starting from different hydroxylated and methoxylated ( S )-chalcones ( Figure 14C ) ( Meinert et al, 2021 ).…”

Trendbericht Biochemie 2022: Späte Funktionalisierung mit Biokatalysatoren aus Naturstoffsynthesen

“…Dort arbeitet sie unter anderem an eisenabhängigen Enzymen für die Wirkstoffsynthese. s.schmidt@rug.nl le Anwendungsbeispiele, die sich nicht auf das Einbringen funktioneller Gruppen beziehen, sondern auf primäre Stoffwechselwege 5) oder Enzyme, die ein Naturstoffgrundgerüst herstellen 6) . Besonders die Weiterentwicklung von Webtools zur Erstellung von SSNs, wie das der Enzyme Function Initative (efi.igb.illinois.edu/ efi-est/), erleichtert den Zugang zu dieser Methode und kann dazu beitragen, Enzymkandidaten für (chemo-)enzymatische Anwendungen bioinformatisch zu entdecken.…”