Glycerolipids in photosynthesis: Composition, synthesis and trafficking

Abstract

Glycerolipids constituting the matrix of photosynthetic membranes, from cyanobacteria to chloroplasts of eukaryotic cells, comprise monogalactosyldiacylglycerol, digalactosyldiacylglycerol, sulfoquinovosyldiacylglycerol and phosphatidylglycerol. This review covers our current knowledge on the structural and functional features of these lipids in various cellular models, from prokaryotes to eukaryotes. Their relative proportions in thylakoid membranes result from highly regulated and compartmentalized metabolic pathways, with a cooperation, in the case of eukaryotes, of non-plastidic compartments. This review also focuses on the role of each of these thylakoid glycerolipids in stabilizing protein complexes of the photosynthetic machinery, which might be one of the reasons for their fascinating conservation in the course of evolution. This article is part of a Special Issue entitled: Dynamic and ultrastructure of bioenergetic membranes and their components.

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

“…MGDG 34:3, DGDG 34:3, and SQDG 34:3 were also very strongly represented in all three leaf stages. MGDG 34:6 species were detected, while DGDG 34:6 and SQDG 34:6 were either not present or below the detection limit, consistent with the current model for the desaturation of acyl chains of thylakoid lipids in the chloroplast (Li-Beisson et al, 2010;Boudière et al, 2014).…”

“…This differs from the situation in Arabidopsis, where levels of all phospholipids show a positive correlation and all glycoglycerolipids show a negative correlation with Pi supply (Dörmann and Benning, 2002). By contrast, 36:x SQDG species, which are synthesized from the ER-derived secondary DAG pool in the chloroplast (Fritz et al, 2007;Li-Beisson et al, 2010;Boudière et al, 2014), clustered in group II (b) and showed the typically documented decrease with increasing Pi supply in H. prostrata. These contrasting responses resulted in an overall sulfolipid profile that responded very little to altered Pi availability.…”

“…In Arabidopsis leaves, 34:x lipid species show mixed acyl chain configurations suggesting biosynthesis from both ER-derived and chloroplast DAG pools, making it hard to determine their precise origin. In Arabidopsis leaves, PG 34:4, SQDG 34:3/34:4, MGDG 34:4 to 34:6, and DGDG 34:1 species almost exclusively carried the C-16 fatty acid in the sn-2 position (DGDG 34:4 species were not detected; Devaiah et al, 2006;Maatta et al, 2012), which would suggest that these lipid species are synthesized from the primary DAG pool in the chloroplast inner envelope membrane via the so-called prokaryotic pathway (Fritz et al, 2007;Li-Beisson et al, 2010;Boudière et al, 2014). In Arabidopsis, both PG and sulfolipids are essential for chloroplast structure and function, but only about 30% of PG species are actually produced in the chloroplast Yu and Benning, 2003).…”

“…PG and SQDG production in the chloroplast are tightly regulated in an antagonist fashion (Essigmann et al, 1998). The fact that H. prostrata appears to produce most of its PG in the chloroplast might account for the fact that only the sulfolipid (and galactolipid) species connected to the primary DAG pool of the chloroplast show the typical compensatory response to lower PG levels in mature leaves (Fritz et al, 2007;Shimojima et al, 2009;Boudière et al, 2014), despite their overall higher P status. The inferred contribution of the prokaryotic pathway for MGDG synthesis rose to as much as 20% in leaves with toxicity symptoms compared with about 2% in leaves of P-limited plants (Supplemental Table S3).…”

The Regulation of Photosynthetic Structure and Function during Nitrogen Deprivation in Chlamydomonas reinhardtii

“…Thylakoid membrane lipids are central to photosynthetic function, including the stabilization of photosynthetic complexes and oxygen evolution (Jarvis et al, 2000;Jones, 2007;Leng et al, 2008;Mizusawa and Wada, 2012;Boudière et al, 2013). The most abundant classes are the neutral lipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) and the anionic lipids sulfoquinovosyldiacylglycerol (SQGD) and phosphatidylglycerol (PG; Frentzen, 2004;Shimojima et al, 2010;Mizusawa and Wada, 2012).…”