Biocatalytic Applications and Mechanistic Insights of Deoxypodophyllotoxin Synthase

Authors:
Publisher website
Google Scholar
Abstract
The lignan (−)-podophyllotoxin possesses significant antiviral and anticancer activities and thus serves as a precursor to several natural products with therapeutic properties. Biosynthesis of podophyllotoxin involves cyclization of (−)-yatein to yield deoxypodophyllotoxin catalyzed by the iron- and α-ketoglutarate-dependent (Fe/α-KG) oxidase deoxypodophyllotoxin synthase (DPS), which completes the tetracyclic core of podophyllotoxin. Herein, (+)-hydroxy-yatein is also shown to be a substrate for DPS, directly affording (−)-podophyllotoxin as the enzymatic product. Moreover, derivatives of (+)-hydroxy-yatein are also found to be substrates providing synthetic precursors to medicines such as etoposide. Mechanistic analyses utilizing isotopologs and diastereomers of the m-dimethoxy analogue of (+)-hydroxy-yatein indicate antarafacial C–C bond formation during the cyclization reaction and remain consistent with cation-mediated cyclization. A crystallographic study of DPS bound with vanadium(IV) oxide, succinate, and (−)-hydroxy-yatein suggests a subtle interplay of steric interactions between the substrate and the active site that can alter the course of the DPS-catalyzed reaction and thus cyclization versus hydroxylation. Finally, an efficient chemoenzymatic approach to (−)-podophyllotoxin is described that relies only on freeze-dried whole cells after DPS overexpression.
Funding Information
  • Division of Chemistry (1845913)
  • National Sun Yat-sen University (NK115P14)
  • National Tsing Hua University (KT115P014)
  • Kaohsiung Medical University (KMU-DK(B)114006)
  • Kaohsiung Medical University (KMU-TB114009-2)
  • Kaohsiung Medical University (KT115P014)
  • Kaohsiung Medical University (NK115P14)
  • National Science and Technology Council (114-2113-M-037- 001)
  • National Science and Technology Council (114-2113-M-037-020)

This publication has 35 references indexed in Scilit: