title: Characterization of Arabidopsis FPS isozymes and FPS gene expression analysis provide insight into the biosynthesis of isoprenoid precursors in seeds.
abstract: Arabidopsis thaliana contains two genes encoding farnesyl diphosphate (FPP) synthase (FPS), the prenyl diphoshate synthase that catalyzes the synthesis of FPP from isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). In this study, we provide evidence that the two Arabidopsis short FPS isozymes FPS1S and FPS2 localize to the cytosol. Both enzymes were expressed in E. coli, purified and biochemically characterized. Despite FPS1S and FPS2 share more than 90% amino acid sequence identity, FPS2 was found to be more efficient as a catalyst, more sensitive to the inhibitory effect of NaCl, and more resistant to thermal inactivation than FPS1S. Homology modelling for FPS1S and FPS2 and analysis of the amino acid differences between the two enzymes revealed an increase in surface polarity and a greater capacity to form surface salt bridges of FPS2 compared to FPS1S. These factors most likely account for the enhanced thermostability of FPS2. Expression analysis of FPS::GUS genes in seeds showed that FPS1 and FPS2 display complementary patterns of expression particularly at late stages of seed development, which suggests that Arabidopsis seeds have two spatially segregated sources of FPP. Functional complementation studies of the Arabidopsis fps2 knockout mutant seed phenotypes demonstrated that under normal conditions FPS1S and FPS2 are functionally interchangeable. A putative role for FPS2 in maintaining seed germination capacity under adverse environmental conditions is discussed.
authors.affiliation: Department of Molecular Genetics, Centre for Research in Agricultural Genomics (CRAG) (CSIC-IRTA-UAB-UB), Campus UAB, Bellaterra (Cerdanyola del Vallès), Barcelona, Spain.
authors.forename: Verónica
authors.initials: V
authors.lastname: Keim
authors.forename: David
authors.initials: D
authors.lastname: Manzano
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Fernández
authors.forename: Marta
authors.initials: M
authors.lastname: Closa
authors.forename: Paola
authors.initials: P
authors.lastname: Andrade
authors.forename: Daniel
authors.initials: D
authors.lastname: Caudepón
authors.forename: Cristina
authors.initials: C
authors.lastname: Bortolotti
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Vega
authors.forename: Montserrat
authors.initials: M
authors.lastname: Arró
authors.forename: Albert
authors.initials: A
authors.lastname: Ferrer
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D051228:Geranyltranstransferase / Q000235:genetics / Q000378:metabolism; D007527:Isoenzymes; D009943:Organophosphorus Compounds; D030821:Plants, Genetically Modified / Q000378:metabolism; D011106:Polyisoprenyl Phosphates / Q000378:metabolism; D012639:Seeds / Q000235:genetics / Q000378:metabolism; D012717:Sesquiterpenes / Q000378:metabolism; D013729:Terpenes / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D009943:Organophosphorus Compounds; D011106:Polyisoprenyl Phosphates; D012717:Sesquiterpenes; D013729:Terpenes; C004808:farnesyl pyrophosphate; D051228:Geranyltranstransferase