The Arabidopsis thaliana FPP synthase isozymes have overlapping and specific functions in isoprenoid biosynthesis, and complete loss of FPP synthase activity causes early developmental arrest

Abstract

SUMMARYFarnesyl diphosphate (FPP) synthase (FPS) catalyses the synthesis of FPP, the major substrate used by cytosolic and mitochondrial branches of the isoprenoid pathway. Arabidopsis contains two farnesyl diphosphate synthase genes, FPS1 and FPS2, that encode isozymes FPS1L (mitochondrial), FPS1S and FPS2 (both cytosolic). Here we show that simultaneous knockout of both FPS genes is lethal for Arabidopsis, and embryo development is arrested at the pre-globular stage, demonstrating that FPP-derived isoprenoid metabolism is essential. In addition, lack of FPS enzyme activity severely impairs male genetic transmission. In contrast, no major developmental and metabolic defects were observed in fps1 and fps2 single knockout mutants, demonstrating the redundancy of the genes. The levels of sterols and ubiquinone, the major mitochondrial isoprenoid, are only slightly reduced in the single mutants. Although one functional FPS gene is sufficient to support isoprenoid biosynthesis for normal growth and development, the functions of FPS1 and FPS2 during development are not completely redundant. FPS1 activity has a predominant role during most of the plant life cycle, and FPS2 appears to have a major role in seeds and during the early stages of seedling development. Lack of FPS2 activity in seeds, but not of FPS1 activity, is associated with a marked reduction in sitosterol content and positive feedback regulation of 3-hydroxy-3-methylglutaryl CoA reductase activity that renders seeds hypersensitive to the 3-hydroxy-3-methylglutaryl CoA reductase inhibitor mevastatin.

A Single Arabidopsis Gene Encodes Two Differentially Targeted Geranylgeranyl Diphosphate Synthase Isoforms

“…1) are presumed to produce FPP and GGPP for ubiquinone synthesis. FPPS1L-defective fps1 mutants only showed a limited decrease in UB-9 levels (Closa et al, 2010), suggesting that the biosynthesis of the ubiquinone solanesyl chain might predominantly rely on the supply of GGPP by GGPPS1, the only GGPPS isoform known to be targeted to mitochondria (Beck et al, 2013;Nagel et al, 2015). However, we found that the T-DNA insertion mutant ggpps1-1 (SAIL_559_G01) contains wild-type levels of UB-9 (Supplemental Fig.…”

“…Interestingly, loss of sG11 activity in g11-3 and g11-4 mutants prevents embryo development to proceed beyond the heart stage (Supplemental Fig. S5; Ruiz-Sola et al, 2016), similar to that observed in ubiquinone-defective mutants (Okada et al, 2004), whereas complete loss of FPPS activity in Arabidopsis fps1 fps2 double mutants blocks embryogenesis at the earlier globular stage (Closa et al, 2010). These results suggest that while FPP-derived isoprenoids are needed for the transition of the embryo from globular to heart stages, progression beyond the heart stage requires ubiquinone or/and a different metabolite produced from sG11-supplied precursors.…”

“…Published methods were used for the extraction, separation, and quantification of photosynthetic pigments (chlorophylls and carotenoids; Rodríguez-Concepción et al, 2004), sterols (Closa et al, 2010), and prenylquinones, including ubiquinone (Martinis et al, 2011).…”

Orthologs of the archaeal isopentenyl phosphate kinase regulate terpenoid production in plants

“…The existence of a cytosolic IP/DMAP pool suggests that IP and DMAP may serve as FPPS inhibitors in vivo, thus controlling carbon flux toward downstream products. AtFPPS1 is one of two Arabidopsis FPPS genes that is highly expressed in vegetative tissue (22) and shows coexpression with AtIPK (Dataset S1). Data are means ± SD (n = 3 independent experiments).…”

Suppressing Farnesyl Diphosphate Synthase Alters Chloroplast Development and Triggers Sterol-Dependent Induction of Jasmonate- and Fe-Related Responses

“…Overexpression of FPS1L or FPS1S causes a cell death/senescence-like phenotype due to a metabolic imbalance that impairs cytokinin biosynthesis (Masferrer et al, 2002;Manzano et al, 2006), whereas overexpression of FPS2 has no apparent detrimental effect on plant growth and development (Bhatia et al, 2015). On the other hand, fps1 and fps2 single knockout mutants are almost indistinguishable from wild-type plants, which is in sharp contrast with the embryo lethality of the fps1/fps2 double mutant (Closa et al, 2010). That work and several other studies have demonstrated that normal functioning of the isoprenoid pathway in the cytosol is indispensable for plant viability.…”