Structural highlights
Function
PULR_MENPI Monoterpene synthase that catalyzes the specific reduction of the 4,8-double bond of (+)-pulegone to produce both (-)-menthone and (+)-isomenthone in a 70:30 ratio. Unable to utilize either (-)-isopiperitenone or (+)-cis-isopulegone, or to catalyze the reverse reaction with (-)-menthone or (+)-isomenthone. Has an absolute requirement for NADPH.
Publication Abstract from PubMed
Monoterpenoids are the main components of plant essential oils and the active components of some traditional Chinese medicinal herbs like Mentha haplocalyx Briq., Nepeta tenuifolia Briq., Perilla frutescens (L.) Britt and Pogostemin cablin (Blanco) Benth. Pulegone reductase is the key enzyme in the biosynthesis of menthol and is required for the stereoselective reduction of the Delta(2,8) double bond of pulegone to produce the major intermediate menthone, thus determining the stereochemistry of menthol. However, the structural basis and mechanism underlying the stereoselectivity of pulegone reductase remain poorly understood. In this study, we characterized a novel (-)-pulegone reductase from Nepeta tenuifolia (NtPR), which can catalyze (-)-pulegone to (+)-menthone and (-)-isomenthone through our RNA-seq, bioinformatic analysis in combination with in vitro enzyme activity assay, and determined the structure of (+)-pulegone reductase from M. piperita (MpPR) by using X-ray crystallography, molecular modeling and docking, site-directed mutagenesis, molecular dynamics simulations, and biochemical analysis. We identified and validated the critical residues in the crystal structure of MpPR involved in the binding of the substrate pulegone. We also further identified that residues Leu56, Val282, and Val284 determine the stereoselectivity of the substrate pulegone, and mainly contributes to the product stereoselectivity. This work not only provides a starting point for the understanding of stereoselectivity of pulegone reductases, but also offers a basis for the engineering of menthone/menthol biosynthetic enzymes to achieve high-titer, industrial-scale production of enantiomerically pure products.
Functional Characterization and Structural Insights Into Stereoselectivity of Pulegone Reductase in Menthol Biosynthesis.,Liu C, Gao Q, Shang Z, Liu J, Zhou S, Dang J, Liu L, Lange I, Srividya N, Lange BM, Wu Q, Lin W Front Plant Sci. 2021 Nov 30;12:780970. doi: 10.3389/fpls.2021.780970., eCollection 2021. PMID:34917113[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Liu C, Gao Q, Shang Z, Liu J, Zhou S, Dang J, Liu L, Lange I, Srividya N, Lange BM, Wu Q, Lin W. Functional Characterization and Structural Insights Into Stereoselectivity of Pulegone Reductase in Menthol Biosynthesis. Front Plant Sci. 2021 Nov 30;12:780970. doi: 10.3389/fpls.2021.780970., eCollection 2021. PMID:34917113 doi:http://dx.doi.org/10.3389/fpls.2021.780970
