Monogalactosyldiacylglycerol synthase isoforms play diverse roles inside and outside the diatom plastid - Université de Montpellier
Article Dans Une Revue The Plant cell Année : 2024

Monogalactosyldiacylglycerol synthase isoforms play diverse roles inside and outside the diatom plastid

Nolwenn Guéguen
Yannick Sérès
Félix Cicéron
  • Fonction : Auteur
Grégory Si Larbi
  • Fonction : Auteur
Denis Falconet
Etienne Deragon
Siraba D Gueye
Damien Le Moigne
Marion Schilling
Mathilde Cussac
Dimitris Petroutsos
Hanhua Hu
Yangmin Gong
Morgane Michaud
Juliette Jouhet
Alberto Amato
Eric Maréchal

Résumé

Diatoms derive from a secondary endosymbiosis event, which occurred when a eukaryotic host cell engulfed a red alga. This led to the formation of a complex plastid enclosed by four membranes: two innermost membranes originating from the red alga chloroplast envelope, and two additional peri- and epiplastidial membranes (PPM, EpM). The EpM is linked to the endoplasmic reticulum (ER). The most abundant membrane lipid in diatoms is monogalactosyldiacylglycerol (MGDG), synthesized by galactosyltransferases called MGDG synthases (MGDs), conserved in photosynthetic eukaryotes and considered to be specific to chloroplast membranes. Similar to angiosperms, a multigenic family of MGDs has evolved in diatoms, but through an independent process. We characterized MGDα, MGDβ and MGDγ in Phaeodactylum tricornutum, combining molecular analyses, heterologous expression in Saccharomyces cerevisiae, and studying overexpressing and CRISPR-Cas9-edited lines. MGDα localizes mainly to thylakoids, MGDβ to the PPM, and MGDγ to the ER and EpM. MGDs have distinct specificities for diacylglycerol, consistent with their localization. Results suggest that MGDα is required for thylakoid expansion under optimal conditions, while MGDβ and MGDγ play roles in plastid and non-plastid membranes and in response to environmental stress. Functional compensation among MGDs likely contributes to diatom resilience under adverse conditions and to their ecological success.
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hal-04731720 , version 1 (11-10-2024)

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Nolwenn Guéguen, Yannick Sérès, Félix Cicéron, Valérie Gros, Grégory Si Larbi, et al.. Monogalactosyldiacylglycerol synthase isoforms play diverse roles inside and outside the diatom plastid. The Plant cell, 2024, 2024, pp.koae275. ⟨10.1093/plcell/koae275⟩. ⟨hal-04731720⟩
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