title: Arabidopsis thaliana squalene epoxidase 1 is essential for root and seed development.
abstract: Squalene epoxidase converts squalene into oxidosqualene, the precursor of all known angiosperm cyclic triterpenoids, which include membrane sterols, brassinosteroid phytohormones, and non-steroidal triterpenoids. In this work, we have identified six putative Arabidopsis squalene epoxidase (SQE) enzymes and used heterologous expression in yeast to demonstrate that three of these enzymes, SQE1, SQE2, and SQE3, can epoxidize squalene. We isolated and characterized Arabidopsis sqe1 mutants and discovered severe developmental defects, including reduced root and hypocotyl elongation. Adult sqe1-3 and sqe1-4 plants have diminished stature and produce inviable seeds. The sqe1-3 mutant accumulates squalene, consistent with a block in the triterpenoid biosynthetic pathway. Therefore, SQE1 function is necessary for normal plant development, and the five SQE-like genes remaining in this mutant are not fully redundant with SQE1.
authors.affiliation: Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005, USA.
authors.forename: Jeanne M
authors.initials: JM
authors.lastname: Rasbery
authors.forename: Hui
authors.initials: H
authors.lastname: Shan
authors.forename: Renee J
authors.initials: RJ
authors.lastname: LeClair
authors.forename: Michael
authors.initials: M
authors.lastname: Norman
authors.forename: Seiichi P T
authors.initials: SP
authors.lastname: Matsuda
authors.forename: Bonnie
authors.initials: B
authors.lastname: Bartel
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000196:embryology / Q000201:enzymology* / Q000254:growth & development; D001483:Base Sequence; D017931:DNA Primers; D017343:Genes, Plant; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012639:Seeds / Q000254:growth & development*; D017386:Sequence Homology, Amino Acid; D050603:Squalene Monooxygenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D011994:Recombinant Proteins; D050603:Squalene Monooxygenase