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First published online March 31, 2006; 10.1104/pp.106.077008 Plant Physiology 141:220-231 (2006) © 2006 American Society of Plant Biologists Maize cDNAs Expressed in Endosperm Encode Functional Farnesyl Diphosphate Synthase with Geranylgeranyl Diphosphate Synthase Activity1Department of Biological Sciences, Lehman College, City University of New York, Bronx, New York 10468 (M.C.-C., C.E.G., C.Z., E.T.W.); and the Graduate School and University Center, City University of New York, New York, New York 10016 (M.C.-C., E.T.W.)
Isoprenoids are the most diverse and abundant group of natural products. In plants, farnesyl diphosphate (FPP) and geranylgeranyl diphosphate (GGPP) are precursors to many isoprenoids having essential functions. Terpenoids and sterols are derived from FPP, whereas gibberellins, carotenoids, casbenes, taxenes, and others originate from GGPP. The corresponding synthases (FPP synthase [FPPS] and GGPP synthase [GGPPS]) catalyze, respectively, the addition of two and three isopentenyl diphosphate molecules to dimethylallyl diphosphate. Maize (Zea mays L. cv B73) endosperm cDNAs encoding isoprenoid synthases were isolated by functional complementation of Escherichia coli cells carrying a bacterial gene cluster encoding all pathway enzymes needed for carotenoid biosynthesis, except for GGPPS. This approach indicated that the maize gene products were functional GGPPS enzymes. Yet, the predicted enzyme sequences revealed FPPS motifs and homology with FPPS enzymes. In vitro assays demonstrated that indeed these maize enzymes produced both FPP and GGPP and that the N-terminal sequence affected the ratio of FPP to GGPP. Their functionality in E. coli demonstrated that these maize enzymes can be coupled with a metabolon to provide isoprenoid substrates for pathway use, and suggests that enzyme bifunctionality can be harnessed. The maize cDNAs are encoded by a small gene family whose transcripts are prevalent in endosperm beginning mid development. These maize cDNAs will be valuable tools for assessing the critical structural properties determining prenyl transferase specificity and in metabolic engineering of isoprenoid pathways, especially in cereal crops.
1 This work was supported by grants from the National Institutes of Health (grant no. S06 GM08225 to E.T.W. and M.C.C.), the City University of New York Collaborative Incentive Program (to E.T.W. and M.C.C.), and the Professional Staff Congress of the City University of New York (to E.T.W.). 2 Present address: Pfizer, Inc., 235 East 42nd St., New York, NY 10017. 3 Present address: Departament de Produccio Vegetal i Ciencia Forestal, Universitat de Lleida, Av. Alcalde Rovira Roure 177, E25198 Lleida, Spain. The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Eleanore T. Wurtzel (wurtzel{at}lehman.cuny.edu). Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.106.077008. * Corresponding author; e-mail wurtzel{at}lehman.cuny.edu; fax 7189607348. Received January 12, 2006; returned for revision March 3, 2006; accepted March 22, 2006. This article has been cited by other articles:
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