Maize cDNAs Expressed in Endosperm Encode Functional Farnesyl Diphosphate Synthase with Geranylgeranyl Diphosphate Synthase Activity

Abstract

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.

The Plastidial 2-C-Methyl-d-Erythritol 4-Phosphate Pathway Provides the Isoprenyl Moiety for Protein Geranylgeranylation in Tobacco BY-2 Cells

“…Under some conditions, FDS enzymes are capable of synthesizing GGPP in vitro (Eberhardt and Rilling, 1975). Furthermore, it was recently shown that maize (Zea mays) endosperm cDNAs coding for FDS, when expressed in an engineered E. coli strain, provided the GGPP needed for carotenoid formation (Cervantes-Cervantes et al, 2006).…”

Structure and Mechanism of an Arabidopsis Medium/Long-Chain-Length Prenyl Pyrophosphate Synthase

“…Based on its product distribution, we rename this enzyme as a PPPS. Intriguingly, most PTSs are monofunctional enzymes that exclusively synthesize single chain-length products (Tarshis et al, 1996;Ogura and Koyama, 1998;Guo et al, 2004;Sun et al, 2005;Chang et al, 2006), whereas a few PTSs from Cryptosporidium parvum, Methanobacterium thermoautotrophicum, Myzus persicae, Picea abies, Toxoplasma godii, and Zea mays also possess the catalytic promiscuity to produce more than one product (Chen and Poulter, 1993;Cervantes-Cervantes et al, 2006;Ling et al, 2007;Artz et al, 2008;Vandermoten et al, 2008;Schmidt et al, 2010).…”

A Bifunctional Geranyl and Geranylgeranyl Diphosphate Synthase Is Involved in Terpene Oleoresin Formation inPicea abies

“…However, products with one more or one fewer C 5 unit than the main product are occasionally reported at low levels in in vitro assays. For example, FPP synthase from maize (Zea mays) produces up to 10% GGPP (Cervantes-Cervantes et al, 2006), and a GPP synthase from the orchid Phalaenopsis bellini produces nearly 20% FPP (Hsiao et al, 2008). However, it is not clear if these enzymes have such a broad product spectrum in vivo.…”