title: An oxidoreductase from 'Alphonso' mango catalyzing biosynthesis of furaneol and reduction of reactive carbonyls.
abstract: Two furanones, furaneol (4-hydroxy-2,5-dimethyl-3(2H)-furanone) and mesifuran (2,5-dimethyl-4-methoxy-3(2H)-furanone), are important constituents of flavor of the Alphonso cultivar of mango (Mangifera indica). To get insights into the biosynthesis of these furanones, we isolated an enone oxidoreductase gene from the Alphonso mango. It has high sequence similarity to an alkenal/one oxidoreductase from cucumber (79% identity) and enone oxidoreductases from tomato (73% identity) and strawberry (72% identity). The complete open reading frame was expressed in E. coli and the (his)6-tagged recombinant protein was purified by affinity chromatography. The purified protein assayed with NADH as a reducing agent converted D-fructose-1,6-diphosphate into furaneol, the immediate precursor of mesifuran. The enzyme was also able to convert two highly reactive carbonyls, 3-buten-2-one and 1-penten-3-one, produced by lipid peroxidation in plants, into their saturated derivatives. Expression profiling in various ripening stages of Alphonso fruits depicted an expression maxima at 10 days after harvest stage, shortly before the appearance of the maximum amount of furanones (completely ripe stage, 15 days after harvest). Although no furanones were detected at the 0 day after harvest stage, significant expression of this gene was detected in the fruits at this stage. Overall, the results suggest that this oxidoreductase plays important roles in Alphonso mango fruits.
authors.affiliation: Plant Molecular Biology Unit, Division of Biochemical Sciences, CSIR-National Chemical Laboratory, Pune, 411 008 India ; Center of Excellence in Epigenetics, Indian Institute of Science Education and Research (IISER), Pune, 411 008 India.
authors.forename: Ram
authors.initials: R
authors.lastname: Kulkarni
authors.forename: Hemangi
authors.initials: H
authors.lastname: Chidley
authors.forename: Ashish
authors.initials: A
authors.lastname: Deshpande
authors.forename: Axel
authors.initials: A
authors.lastname: Schmidt
authors.forename: Keshav
authors.initials: K
authors.lastname: Pujari
authors.forename: Ashok
authors.initials: A
authors.lastname: Giri
authors.forename: Jonathan
authors.initials: J
authors.lastname: Gershenzon
authors.forename: Vidya
authors.initials: V
authors.lastname: Gupta
keywords: Detoxification; Enone oxidoreductase; Flavor; Mangifera indica; Ripening