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Identification and characterization of sterol acyltransferases responsible for steryl ester biosynthesis in tomato
Lara, Juan A. (Centre de Recerca en Agrigenòmica)
Burciaga-Monge, Alma (Centre de Recerca en Agrigenòmica)
Chávez, Angel (Centre de Recerca en Agrigenòmica)
Revés, Marc (Universitat de Barcelona. Institut de Biomedicina)
Lavilla, Rodolfo (Universitat de Barcelona. Institut de Biomedicina)
Arró i Plans, Montserrat (Centre de Recerca en Agrigenòmica)
Boronat i Margosa, Albert (Centre de Recerca en Agrigenòmica)
Altabella Artigas, Teresa (Centre de Recerca en Agrigenòmica)
Ferrer i Prats, Albert (Centre de Recerca en Agrigenòmica)

Date: 2018
Abstract: Steryl esters (SEs) serve as a storage pool of sterols that helps to maintain proper levels of free sterols (FSs) in cell membranes throughout plant growth and development, and participates in the recycling of FSs and fatty acids released from cell membranes in aging tissues. SEs are synthesized by sterol acyltransferases, a family of enzymes that catalyze the transfer of fatty acil groups to the hydroxyl group at C-3 position of the sterol backbone. Sterol acyltransferases are categorized into acyl-CoA:sterol acyltransferases (ASAT) and phospholipid:sterol acyltransferases (PSAT) depending on whether the fatty acyl donor substrate is a long-chain acyl-CoA or a phospolipid. Until now, only Arabidopsis ASAT and PSAT enzymes (AtASAT1 and AtPSAT1) have been cloned and characterized in plants. Here we report the identification, cloning, and functional characterization of the tomato (Solanum lycopersicum cv. Micro-Tom) orthologs. SlPSAT1 and SlASAT1 were able to restore SE to wild type levels in the Arabidopsis psat1-2 and asat1-1 knock-out mutants, respectively. Expression of SlPSAT1 in the psat1-2 background also prevented the toxicity caused by an external supply of mevalonate and the early senescence phenotype observed in detached leaves of this mutant, whereas expression of SlASAT1 in the asat1-1 mutant revealed a clear substrate preference of the tomato enzyme for the sterol precursors cycloartenol and 24-methylene cycloartanol. Subcellular localization studies using fluorescently tagged SlPSAT1 and SlASAT1 proteins revealed that SlPSAT1 localize in cytoplasmic lipid droplets (LDs) while, in contrast to the endoplasmic reticulum (ER) localization of AtASAT1, SlASAT1 resides in the plasma membrane (PM). The possibility that PM-localized SlASAT1 may act catalytically in trans on their sterol substrates, which are presumably embedded in the ER membrane, is discussed. The widespread expression of SlPSAT1 and SlASAT1 genes in different tomato organs together with their moderate transcriptional response to several stresses suggests a dual role of SlPSAT1 and SlASAT1 in tomato plant and fruit development and the adaptive responses to stress. Overall, this study contributes to enlarge the current knowledge on plant sterol acyltransferases and set the basis for further studies aimed at understanding the role of SE metabolism in tomato plant growth and development.
Note: Número d'acord de subvenció MINECO/AGL2013-43522-R
Note: Número d'acord de subvenció MINECO/AGL2017-88842-R
Note: Número d'acord de subvenció AGAUR/2014/SGR-1434
Note: Número d'acord de subvenció MINECO/SEV2015-0533
Rights: Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original. Creative Commons
Language: Anglès.
Document: article ; recerca ; publishedVersion
Subject: Arabidopsis ; Conjugated sterols ; Solanum lycopersicum ; Sterol esterification ; Stress response ; Subcellular localization
Published in: Frontiers in Plant Science, Vol. 9 (May 2018) , art. 588, ISSN 1664-462X

DOI: 10.3389/fpls.2018.00588
PMID: 29868054


18 p, 5.0 MB

The record appears in these collections:
Research literature > UAB research groups literature > Research Centres and Groups (scientific output) > Experimental sciences > CRAG (Centre for Research in Agricultural Genomics)
Articles > Research articles
Articles > Published articles

 Record created 2018-12-21, last modified 2019-02-15



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