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Navarro Gallón SM, Elejalde-Palmett C, Daudu D, Liesecke F, Jullien F, Papon N, Dugé de Bernonville T, Courdavault V, Lanoue A, Oudin A, Glévarec G, Pichon O, Clastre M, St-Pierre B, Atehortùa L, Yoshikawa N, Giglioli-Guivarc'h N, Besseau S. Virus-induced gene silencing of the two squalene synthase isoforms of apple tree (Malus × domestica L.) negatively impacts phytosterol biosynthesis, plastid pigmentation and leaf growth. PLANTA 2017; 246:45-60. [PMID: 28349256 DOI: 10.1007/s00425-017-2681-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 03/17/2017] [Indexed: 05/24/2023]
Abstract
The use of a VIGS approach to silence the newly characterized apple tree SQS isoforms points out the biological function of phytosterols in plastid pigmentation and leaf development. Triterpenoids are beneficial health compounds highly accumulated in apple; however, their metabolic regulation is poorly understood. Squalene synthase (SQS) is a key branch point enzyme involved in both phytosterol and triterpene biosynthesis. In this study, two SQS isoforms were identified in apple tree genome. Both isoforms are located at the endoplasmic reticulum surface and were demonstrated to be functional SQS enzymes using an in vitro activity assay. MdSQS1 and MdSQS2 display specificities in their expression profiles with respect to plant organs and environmental constraints. This indicates a possible preferential involvement of each isoform in phytosterol and/or triterpene metabolic pathways as further argued using RNAseq meta-transcriptomic analyses. Finally, a virus-induced gene silencing (VIGS) approach was used to silence MdSQS1 and MdSQS2. The concomitant down-regulation of both MdSQS isoforms strongly affected phytosterol synthesis without alteration in triterpene accumulation, since triterpene-specific oxidosqualene synthases were found to be up-regulated to compensate metabolic flux reduction. Phytosterol deficiencies in silenced plants clearly disturbed chloroplast pigmentation and led to abnormal development impacting leaf division rather than elongation or differentiation. In conclusion, beyond the characterization of two SQS isoforms in apple tree, this work brings clues for a specific involvement of each isoform in phytosterol and triterpene pathways and emphasizes the biological function of phytosterols in development and chloroplast integrity. Our report also opens the door to metabolism studies in Malus domestica using the apple latent spherical virus-based VIGS method.
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Affiliation(s)
- Sandra M Navarro Gallón
- EA2106 Biomolécules et Biotechnologies Végétales, Université François Rabelais de Tours, Tours, France
- Laboratorio de Biotecnologıa, Sede de Investigacion Universitaria, Universidad de Antioquia, Medellin, Colombia
| | - Carolina Elejalde-Palmett
- EA2106 Biomolécules et Biotechnologies Végétales, Université François Rabelais de Tours, Tours, France
| | - Dimitri Daudu
- EA2106 Biomolécules et Biotechnologies Végétales, Université François Rabelais de Tours, Tours, France
| | - Franziska Liesecke
- EA2106 Biomolécules et Biotechnologies Végétales, Université François Rabelais de Tours, Tours, France
| | - Frédéric Jullien
- EA3061 Laboratoire de Biotechnologies Végétales appliquées aux plantes aromatiques et médicinales, Université Jean Monnet de Saint Etienne, Saint Etienne, France
| | - Nicolas Papon
- EA3142 Groupe d'Etude des Interactions Hôte-Pathogène, Université d'Angers, Angers, France
| | | | - Vincent Courdavault
- EA2106 Biomolécules et Biotechnologies Végétales, Université François Rabelais de Tours, Tours, France
| | - Arnaud Lanoue
- EA2106 Biomolécules et Biotechnologies Végétales, Université François Rabelais de Tours, Tours, France
| | - Audrey Oudin
- EA2106 Biomolécules et Biotechnologies Végétales, Université François Rabelais de Tours, Tours, France
| | - Gaëlle Glévarec
- EA2106 Biomolécules et Biotechnologies Végétales, Université François Rabelais de Tours, Tours, France
| | - Olivier Pichon
- EA2106 Biomolécules et Biotechnologies Végétales, Université François Rabelais de Tours, Tours, France
| | - Marc Clastre
- EA2106 Biomolécules et Biotechnologies Végétales, Université François Rabelais de Tours, Tours, France
| | - Benoit St-Pierre
- EA2106 Biomolécules et Biotechnologies Végétales, Université François Rabelais de Tours, Tours, France
| | - Lucia Atehortùa
- Laboratorio de Biotecnologıa, Sede de Investigacion Universitaria, Universidad de Antioquia, Medellin, Colombia
| | | | | | - Sébastien Besseau
- EA2106 Biomolécules et Biotechnologies Végétales, Université François Rabelais de Tours, Tours, France.
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A rapid, high-throughput method for quantitative determination of ethanol tolerance in Saccharomyces cerevisiae. ANN MICROBIOL 2013. [DOI: 10.1007/s13213-012-0518-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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Szkopińska A, Swiezewska E, Karst F. The regulation of activity of main mevalonic acid pathway enzymes: farnesyl diphosphate synthase, 3-hydroxy-3-methylglutaryl-CoA reductase, and squalene synthase in yeast Saccharomyces cerevisiae. Biochem Biophys Res Commun 2000; 267:473-7. [PMID: 10623644 DOI: 10.1006/bbrc.1999.1981] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The co-regulation of the main mevalonic acid pathway enzymes was investigated in the yeast Saccharomyces cerevisiae. It was found that a 6-fold increase in FPPS activity compared with that of the wild-type strain FL100 did not cause significant changes in HMG-CoA reductase activity, while the amounts of synthesized dolichols and ergosterol increased by 80 and 32%, respectively. The disruption of the SQS gene in the strain grown in the presence of ergosterol repressed the activities of both FPP synthase and HMG-CoA reductase to a comparable degree, whereas in the same strain starved for ergosterol the activity of FPPS was 10-fold higher and HMG-CoA reductase activity was practically unchanged. We show that FPPS is the enzyme that regulates the flow rate of synthesized mevalonic acid pathway products independent of HMG-CoA reductase and SQS.
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Affiliation(s)
- A Szkopińska
- Institute of Biochemistry, Polish Academy of Sciences, ul. Pawińskiego 5a, Warszawa, 02-106, Poland.
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Swan TM, Watson K. Stress tolerance in a yeast lipid mutant: membrane lipids influence tolerance to heat and ethanol independently of heat shock proteins and trehalose. Can J Microbiol 1999; 45:472-9. [PMID: 10453475 DOI: 10.1139/w99-033] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The response of a yeast unsaturated fatty acid auxotroph, defective in delta 9-desaturase activity, to heat and ethanol stresses was examined. The most heat- and ethanol-tolerant cells had membranes enriched with oleic acid (C18:1), followed in order by cells enriched with linoleic (C18:2) and linolenic (C18:3) acids. Cells subjected to a heat shock (25-37 degrees C for 30 min) accumulated trehalose and synthesized typical heat shock proteins. Although there were no obvious differences in protein profiles attributable to lipid supplementation of the mutant, relative protein synthesis as determined by densitometric analysis of autoradiograms suggested that hsp expression was different. However, there was no consistent relationship between the synthesis of heat shock proteins and the acquisition of thermotolerance in the lipid supplemented auxotroph or related wild type. Furthermore, trehalose accumulation was also not closely related to stress tolerance. On the other hand, the data presented indicated a more consistent role for membrane lipid composition in stress tolerance than trehalose, heat shock proteins, or ergosterol. We suggest that the sensitivity of C18:3-enriched cells to heat and ethanol may be attributable to membrane damage associated with increases in membrane fluidity and oxygen-derived free radical attack of membrane lipids.
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Affiliation(s)
- T M Swan
- School of Biological Sciences, University of New England, Armidale, Australia
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Grabowska D, Karst F, Szkopińska A. Effect of squalene synthase gene disruption on synthesis of polyprenols in Saccharomyces cerevisiae. FEBS Lett 1998; 434:406-8. [PMID: 9742963 DOI: 10.1016/s0014-5793(98)01019-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Biosynthesis of polyprenols was investigated in a wild-type strain of Saccharomyces cerevisiae and a squalene synthase deficient strain auxotrophic for ergosterol. The quantitative data showed that disruption of squalene synthase gene caused a 6-fold increase in the synthesis of polyprenols in vitro in comparison with the wild-type strain. Microsomal preparation from the deleted strain only slightly reacted to the additional exogenous FPP, while that from the wild-type strain presented a 4-fold increase of polyprenol synthesis. Restoration of ergosterol synthesis, by introducing ERG9 functional allele into the deleted strain resulted in a significant lowering of polyprenol synthesis, indicating the immediate shift of the common substrate (FPP) to the sterol pathway. The role of squalene synthase in the regulation of polyprenol synthesis and 'flow diversion hypothesis' is discussed.
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Affiliation(s)
- D Grabowska
- Institute of Biochemistry and Biophysics, PAN, Warszawa, Poland
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Kribii R, Arró M, Del Arco A, González V, Balcells L, Delourme D, Ferrer A, Karst F, Boronat A. Cloning and characterization of the Arabidopsis thaliana SQS1 gene encoding squalene synthase--involvement of the C-terminal region of the enzyme in the channeling of squalene through the sterol pathway. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 249:61-9. [PMID: 9363754 DOI: 10.1111/j.1432-1033.1997.00061.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Squalene synthase (SQS) catalyzes the first committed step of the sterol biosynthetic pathway. A full-length Arabidopsis thaliana SQS cDNA has been isolated by combining library screening and PCR-based approaches. Arabidopsis SQS is encoded by a small gene family of two genes (SQS1 and SQS2) which are organized in a tandem array. SQS1 and SQS2 have an identical organization with regard to intron positions and exon sizes and encode SQS isoforms showing a high level of sequence conservation (79% identity and 88% similarity). The isolated cDNA has been assigned to the SQS1 gene product, SQS1. RNA blot analysis has shown that the 1.6-kb SQS1 mRNA is detected in all plant tissues analyzed (inflorescenses, leaves, stems and roots) although the transcript is especially abundant in roots. Arabidopsis SQS1 isoform is unable to complement the SQS-defective Saccharomyces cerevisiae strain 5302, although SQS activity was detected in the microsomal fraction of the transformed yeast strain. However, a chimeric SQS resulting from the replacement of the 66 C-terminal residues of the Arabidopsis enzyme by the 111 C-terminal residues of the Schizosaccharomyces pombe enzyme was able to confer ergosterol prototrophy to strain 5302. Labeling studies using [3H]farnesyl-P2 and microsomal fractions obtained from yeast strains expressing either Arabidopsis SQS1 or chimeric Arabidopsis/S. pombe SQS derivatives indicated that the C-terminal region of the enzyme is involved in the channeling of squalene through the yeast sterol pathway.
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Affiliation(s)
- R Kribii
- Laboratoire de Génétique Physiologique et Moléculaire, Institut de Biologie Moléculaire et d'Ingénierie Génétique, Université de Poitiers, France
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