title: Molecular cloning of mevalonate pathway genes from Taraxacum brevicorniculatum and functional characterisation of the key enzyme 3-hydroxy-3-methylglutaryl-coenzyme A reductase.
abstract: Taraxacum brevicorniculatum is known to produce high quality rubber. The biosynthesis of rubber is dependent on isopentenyl pyrophosphate (IPP) precursors derived from the mevalonate (MVA) pathway. The cDNA sequences of seven MVA pathway genes from latex of T. brevicorniculatum were isolated, including three cDNA sequences encoding for 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductases (TbHMGR1-3). Expression analyses indicate an important role of TbHMGR1 as well as for the HMG-CoA synthase (TbHMGS), the diphosphomevalonate decarboxylase and the mevalonate kinase in the provision of precursors for rubber biosynthesis. The amino acid sequences of the TbHMGRs show the typical motifs described for plant HMGRs such as two transmembrane domains and a catalytic domain containing two HMG-CoA and two NADP(H) binding sites. The functionality of the HMGRs was demonstrated by complementation assay using an IPP auxotroph mutant of Escherichia coli. Furthermore, the transient expression of the catalytic domains of TbHMGR1 and TbHMGR2 in Nicotiana benthamiana resulted in a strong accumulation of sterol precursors, one of the major groups of pathway end-products.
authors.affiliation: Institut für Biologie und Biotechnologie der Pflanzen, Westfälische Wilhelms-Universität Münster, Hindenburgplatz 55, 48143, Münster, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: van Deenen
authors.forename: Anne-Lena
authors.initials: AL
authors.lastname: Bachmann
authors.forename: Thomas
authors.initials: T
authors.lastname: Schmidt
authors.forename: Hubert
authors.initials: H
authors.lastname: Schaller
authors.forename: Jennifer
authors.initials: J
authors.lastname: Sand
authors.forename: Dirk
authors.initials: D
authors.lastname: Prüfer
authors.forename: Christian
authors.initials: C
authors.lastname: Schulze Gronover
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D053898:Biosynthetic Pathways / Q000187:drug effects / Q000235:genetics*; D020134:Catalytic Domain; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics*; D005816:Genetic Complementation Test; D006903:Hydroxymethylglutaryl CoA Reductases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008148:Lovastatin / Q000494:pharmacology; D008798:Mevalonic Acid / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000187:drug effects / Q000235:genetics; D010641:Phenotype; D010802:Phylogeny; D018517:Plant Roots / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D013261:Sterols / Q000378:metabolism; D031205:Taraxacum / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D014026:Nicotiana / Q000187:drug effects / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D013261:Sterols; D008148:Lovastatin; D006903:Hydroxymethylglutaryl CoA Reductases; D008798:Mevalonic Acid