This Article Full Text Full Text (PDF) All Versions of this Article: 18/4/1023    most recent tpc.105.039784v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (7) Citing Articles via Google Scholar Google Scholar Articles by Raab, T. Articles by Muñoz-Blanco, J. Search for Related Content PubMed PubMed Citation Articles by Raab, T. Articles by Muñoz-Blanco, J. Agricola Articles by Raab, T. Articles by Muñoz-Blanco, J.

FaQR, Required for the Biosynthesis of the Strawberry Flavor Compound 4-Hydroxy-2,5-Dimethyl-3(2H)-Furanone, Encodes an Enone Oxidoreductase

^a Institute of Pharmacy and Food Chemistry, University of Würzburg, 97074 Würzburg, Germany
^b Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, 14071 Córdoba, Spain
^c Biomolecular Food Technology, Technical University Munich, 85354 Freising, Germany

² To whom correspondence should be addressed. E-mail schwab{at}wzw.tum.de; fax 49-8161-548-595.

The flavor of strawberry (Fragaria x ananassa) fruit is dominated by an uncommon group of aroma compounds with a 2,5-dimethyl-3(H)-furanone structure. We report the characterization of an enzyme involved in the biosynthesis of 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF; Furaneol), the key flavor compound in strawberries. Protein extracts were partially purified, and the observed distribution of enzymatic activity correlated with the presence of a single polypeptide of 37 kD. Sequence analysis of two peptide fragments showed total identity with the protein sequence of a strongly ripening-induced, auxin-dependent putative quinone oxidoreductase, Fragaria x ananassa quinone oxidoreductase (FaQR). The open reading frame of the FaQR cDNA consists of 969 bp encoding a 322–amino acid protein with a calculated molecular mass of 34.3 kD. Laser capture microdissection followed by RNA extraction and amplification demonstrated the presence of FaQR mRNA in parenchyma tissue of the strawberry fruit. The FaQR protein was functionally expressed in Escherichia coli, and the monomer catalyzed the formation of HDMF. After chemical synthesis and liquid chromatography–tandem mass spectrometry analysis, 4-hydroxy-5-methyl-2-methylene-3(2H)-furanone was confirmed as a substrate of FaQR and the natural precursor of HDMF. This study demonstrates the function of the FaQR enzyme in the biosynthesis of HDMF as enone oxidoreductase and provides a foundation for the improvement of strawberry flavor and the biotechnological production of HDMF.

This article has been cited by other articles:

				M. Griesser, F. Vitzthum, B. Fink, M. L. Bellido, C. Raasch, J. Munoz-Blanco, and W. Schwab Multi-substrate flavonol O-glucosyltransferases from strawberry (Fragariaxananassa) achene and receptacle J. Exp. Bot., July 1, 2008; 59(10): 2611 - 2625. [Abstract] [Full Text] [PDF]

				M. Griesser, T. Hoffmann, M. L. Bellido, C. Rosati, B. Fink, R. Kurtzer, A. Aharoni, J. Munoz-Blanco, and W. Schwab Redirection of Flavonoid Biosynthesis through the Down-Regulation of an Anthocyanidin Glucosyltransferase in Ripening Strawberry Fruit Plant Physiology, April 1, 2008; 146(4): 1528 - 1539. [Abstract] [Full Text] [PDF]