Emergence of a proton exchange-based isomerization and lactonization mechanism in the plant coumarin synthase COSY.

Autor: Kim CY; Whitehead Institute for Biomedical Research, Cambridge, MA, 02142, USA.; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA., Mitchell AJ; Whitehead Institute for Biomedical Research, Cambridge, MA, 02142, USA., Kastner DW; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.; Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA., Albright CE; Whitehead Institute for Biomedical Research, Cambridge, MA, 02142, USA., Gutierrez MA; Whitehead Institute for Biomedical Research, Cambridge, MA, 02142, USA., Glinkerman CM; Whitehead Institute for Biomedical Research, Cambridge, MA, 02142, USA., Kulik HJ; Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA., Weng JK; Whitehead Institute for Biomedical Research, Cambridge, MA, 02142, USA. wengj@wi.mit.edu.; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA. wengj@wi.mit.edu.
Jazyk: angličtina
Zdroj: Nature communications [Nat Commun] 2023 Feb 03; Vol. 14 (1), pp. 597. Date of Electronic Publication: 2023 Feb 03.
DOI: 10.1038/s41467-023-36299-1
Abstrakt: Plants contain rapidly evolving specialized enzymes that support the biosynthesis of functionally diverse natural products. In coumarin biosynthesis, a BAHD acyltransferase-family enzyme COSY was recently discovered to accelerate coumarin formation as the only known BAHD enzyme to catalyze an intramolecular acyl transfer reaction. Here we investigate the structural and mechanistic basis for COSY's coumarin synthase activity. Our structural analyses reveal an unconventional active-site configuration adapted to COSY's specialized activity. Through mutagenesis studies and deuterium exchange experiments, we identify a unique proton exchange mechanism at the α-carbon of the o-hydroxylated trans-hydroxycinnamoyl-CoA substrates during the catalytic cycle of COSY. Quantum mechanical cluster modeling and molecular dynamics further support this key mechanism for lowering the activation energy of the rate-limiting trans-to-cis isomerization step in coumarin production. This study unveils an unconventional catalytic mechanism mediated by a BAHD-family enzyme, and sheds light on COSY's evolutionary origin and its recruitment to coumarin biosynthesis in eudicots.
(© 2023. The Author(s).)
Databáze: MEDLINE
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