The isoprenoid pathway is responsible for the generation of a wide range of products that are crucial for cellular processes; namely, cholesterol synthesis, protein glycosylation, growth control and synthesis of several hormones. Farnesyl diphosphate synthase (FPS), a key enzyme in this pathway, is usually considered to be cytosolic/peroxisomal. However, significant enzymatic activity has also been detected in rat liver mitochondria, although none of the mammalian FPS genes characterized to date contain sequences coding for mitochondrial transit peptides.
View Article and Find Full Text PDF1-Deoxy-D-xylulose 5-phosphate reductoisomerase (DXR) catalyzes the first committed step of the 2-C-methyl-D-erythritol 4-phosphate pathway for isoprenoid biosynthesis. In Arabidopsis, DXR is encoded by a single-copy gene. We have cloned a full-length cDNA corresponding to this gene.
View Article and Find Full Text PDFTo investigate the contribution of farnesyl diphosphate synthase (FPS) to the overall control of the mevalonic acid pathway in plants, we have generated transgenic Arabidopsis thaliana overexpressing the Arabidopsis FPS1S isoform. Despite high levels of FPS activity in transgenic plants (8- to 12-fold as compared to wild-type plants), the content of sterols and the levels of 3-hydroxy-3-methylglutaryl-CoA reductase activity in leaves were similar to those in control plants. Plants overexpressing FPS1S showed a cell death/senescence-like phenotype and grew less vigorously than wild-type plants.
View Article and Find Full Text PDFFarnesyl diphosphate synthase (FPS), the enzyme that catalyses the synthesis of farnesyl diphosphate (FPP) from isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), is considered a regulatory enzyme of plant isoprenoid biosynthesis. The promoter regions of the FPS1 and FPS2 genes controlling the expression of isoforms FPS1S and FPS2, respectively, were fused to the beta-glucuronidase (GUS) reporter gene and introduced into Arabidopsis thaliana plants. The FPS1S:GUS gene is widely expressed in all plant tissues throughout development, thus supporting a role for FPS1S in the synthesis of isoprenoids serving basic plant cell functions.
View Article and Find Full Text PDFThe enzyme dehydrodolichyl diphosphate (dedol-PP) synthase is a cis-prenyltransferase that catalyzes the synthesis of dedol-PP, the long-chain polyprenyl diphosphate used as a precursor for the synthesis of dolichyl phosphate. Here we report the cloning and characterization of a cDNA from Arabidopsis thaliana encoding dedol-PP synthase. The identity of the cloned enzyme was confirmed by functional complementation of a yeast mutant strain defective in dedol-PP synthase activity together with the detection of high levels of dedol-PP synthase activity in the transformed yeast mutant.
View Article and Find Full Text PDFTwo DNA fragments, AP-1 and AP-2, encoding amino acid sequences closely related to Ser/Thr protein phosphatases were amplified from Arabidopsis thaliana genomic DNA. Fragment AP-1 was used to screen A. thaliana cDNA libraries and several positive clones were isolated.
View Article and Find Full Text PDF