Allelic mutant series reveal distinct functions for Arabidopsis cycloartenol synthase 1 in cell viability and plastid biogenesis
| Autor: | Marc Van Montagu, Toshiya Muranaka, Masashi Suzuki, Vincent Compagnon, Elena Babiychuk, Hubert Schaller, Pierrette Bouvier-Navé, Sergei Kushnir |
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| Přispěvatelé: | Institut de biologie moléculaire des plantes (IBMP), Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA) |
| Rok vydání: | 2008 |
| Předmět: |
Squalene
0106 biological sciences Cell Survival Molecular Sequence Data Mutant Arabidopsis [SDV.BC]Life Sciences [q-bio]/Cellular Biology 01 natural sciences Gas Chromatography-Mass Spectrometry 03 medical and health sciences chemistry.chemical_compound Arabidopsis thaliana Plastids Plastid Intramolecular Transferases DNA Primers 030304 developmental biology 0303 health sciences Multidisciplinary Base Sequence Molecular Structure Plant Stems biology Reverse Transcriptase Polymerase Chain Reaction food and beverages Sequence Analysis DNA Biological Sciences biology.organism_classification Sterol Microscopy Electron Phenotype Cycloartenol synthase chemistry Biochemistry Mutation biology.protein Cycloartenol Biogenesis 010606 plant biology & botany |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America Proceedings of the National Academy of Sciences of the United States of America, National Academy of Sciences, 2008, 105, pp.3163-3168 |
| ISSN: | 1091-6490 0027-8424 |
| DOI: | 10.1073/pnas.0712190105 |
| Popis: | Sterols have multiple functions in all eukaryotes. In plants, sterol biosynthesis is initiated by the enzymatic conversion of 2,3-oxidosqualene to cycloartenol. This reaction is catalyzed by cycloartenol synthase 1 (CAS1), which belongs to a family of 13 2,3-oxidosqualene cyclases in Arabidopsis thaliana . To understand the full scope of sterol biological functions in plants, we characterized allelic series of cas1 mutations. Plants carrying the weak mutant allele cas1–1 were viable but developed albino inflorescence shoots because of photooxidation of plastids in stems that contained low amounts of carotenoids and chlorophylls. Consistent with the CAS1 catalyzed reaction, mutant tissues accumulated 2,3-oxidosqualene. This triterpenoid precursor did not increase at the expense of the pathway end products. Two strong mutations, cas1–2 and cas1–3 , were not transmissible through the male gametes, suggesting a role for CAS1 in male gametophyte function. To validate these findings, we analyzed a conditional CRE/loxP recombination-dependent cas1–2 mutant allele. The albino phenotype of growing leaf tissues was a typical defect observed shortly after the CRE/loxP -induced onset of CAS1 loss of function. In the induced cas1–2 seedlings, terminal phenotypes included arrest of meristematic activity, followed by necrotic death. Mutant tissues accumulated 2,3-oxidosqualene and contained low amounts of sterols. The vital role of sterols in membrane functioning most probably explains the requirement of CAS1 for plant cell viability. The observed impact of cas1 mutations on a chloroplastic function implies a previously unrecognized role of sterols or triterpenoid metabolites in plastid biogenesis. |
| Databáze: | OpenAIRE |
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