Role of phosphatidic acid in plant galactolipid synthesis

Abstract

Phosphatidic acid (PA) is a precursor metabolite for phosphoglycerolipids and also for galactoglycerolipids, which are essential lipids for formation of plant membranes. PA has in addition a main regulatory role in a number of developmental processes notably in the response of the plant to environmental stresses. We review here the different pools of PA dispatched at different locations in the plant cell and how these pools are modified in different growth conditions, particularly during plastid membrane biogenesis and when the plant is exposed to phosphate deprivation. We analyze how these modifications can affect galactolipid synthesis by tuning the activity of MGD1 enzyme allowing a coupling of phosphoand galactolipid metabolisms. Some mechanisms are considered to explain how physicochemical properties of PA allow this lipid to act as a central internal sensor in plant physiology.

Membrane Glycerolipid Remodeling Triggered by Nitrogen and Phosphorus Starvation inPhaeodactylum tricornutum

“…Phospholipid-to-nonphosphorus lipid replacement has been studied in depth in the plant Arabidopsis (Arabidopsis thaliana; Benning and Ohta, 2005;Shimojima and Ohta, 2011;Boudière et al, 2012;Dubots et al, 2012;Nakamura, 2013;Petroutsos et al, 2014). In Arabidopsis, PC and PG contents decrease upon P starvation, and the synthesis of plastid glycolipids (i.e.…”

“…Upon P shortage, the eukaryotic pathway is activated; PC hydrolysis releases a diacyl intermediate, which is then transferred to the plastid to synthesize MGDG and DGDG (Jouhet et al, 2003), creating a virtuous recycling of lipid intermediates between phospholipid breakdown and galactolipid increase. The Arabidopsis response to low P combines a rapid metabolic regulation, coupling MGDG synthesis to the phospholipid status (Dubots et al, , 2012, with a longer term genomic reprogramming (Misson et al, 2005;Morcuende et al, 2007) characterized by the up-regulation of phospholipases C and D (hydrolyzing phospholipids) and of monogalactosyldiacyl and digalactosyldiacyl isoforms (the galactosyltransferases synthesizing MGDG and DGDG, respectively). In P-starved conditions, a PG-to-SQDG replacement is observed and is considered to be a ubiquitous phenomenon in photosynthetic organisms, enabling the preservation of an anionic lipid environment to the photosystems in the thylakoids (Boudière et al, 2014).…”

Mono- and digalactosyldiacylglycerol composition of dinoflagellates. VII. Evidence against galactolipid production and plastid presence in the heterotrophic, basal dinoflagellate, Oxyrrhis marina

“…Biosynthesis of MGDG and DGDG depends absolutely on the presence of two enzymes, MGDG and DGDG synthases, which transfer galactose from UDP-galactose to a diglyceride and MGDG, respectively (Dubots et al, 2012). Although sequences for plastid-targeted proteins have been observed by Slamovits & Keeling (2008) in O. marina grown unialgally in the absence of prey, which will likely minimize potential interference from prey-derived RNA, they did not identify any plastid-targeted genes necessary for synthesis of MGDG and DGDG.…”

Lipid Biosynthesis and Protein Concentration Respond Uniquely to Phosphate Supply during Leaf Development in Highly Phosphorus-Efficient Hakea prostrata

“…The moderate transcriptional response in H. prostrata shows that while this species has not entirely lost the capacity to regulate P use for lipid metabolism through changes in gene expression, the magnitude of the response is greatly reduced compared with that in other plants. While profiles of Arabidopsis transcripts correlate well with changes in lipid profiles in response to environment (Szymanski et al, 2014), lipid metabolism in H. prostrata appears to be mostly regulated at the posttranscriptional level, perhaps through other mechanisms that are known to operate in other species like selective RNA translation and protein turnover (Galland et al, 2014) or allosteric enzyme regulation by PA and other lipid metabolites (Ohlrogge and Browse, 1995;Dubots et al, 2012). H. prostrata is restricted to low-P environments.…”