Acyl-CoA:lysophosphatidylcholine acyltransferases (LPCATs) of Camelina sativa seeds: biochemical properties and function

Abstract

Main conclusion The transfer of polyunsaturated fatty acids from phosphatidylcholine to other lipids involves several enzymes. In Camelina sativa seeds, acyl-CoA:lysophosphatidylcholine acyltransferases could be one of the most important players in this process.Abstract The transfer of polyunsaturated fatty acids from the location of their synthesis (phosphatidylcholine) to other lipids, e.g., triacylglycerol, remains insufficiently understood. Several enzymes could be involved in this process. One of these enzymes is acyl-CoA:lysophosphatidylcholine acyltransferases (LPCATs). In Camelina sativa seeds, LPCATs could be one of the most important players in this process. Our data clearly indicate that the CsLPCATs present in developing seeds have the potential to transfer almost all polyunsaturated fatty acids synthesised on phosphatidylcholine to the acyl-CoA pool. CsLPCAT activity is the highest at 30 °C, and the enzymes operate well at a pH of 7.0-11.0, with the best activity at a pH of 9.0. The activity of CsLPCATs was inhibited by calcium and magnesium ions at a concentration of 0.05-2 mM. In the forward reaction, CsLPCATs preferentially utilise 18:2-CoA; however, other C18 unsaturated fatty acids are also well accepted. In the backward reactions, there is no clear discrimination between the C18 unsaturated fatty acids utilised by the enzymes for phosphatidylcholine remodelling. The activity of CsLPCATs does not differ much between the stages of seed development.

LPEATs Tailor Plant Phospholipid Composition through Adjusting Substrate Preferences to Temperature

“…The highest activity towards each of the tested acyl donors was observed at 30 °C. The same temperature optimum was also noticed for other LPLAT enzymes present in C. sativa [ 26 , 28 ]. Declined activity was mainly observed at 10 °C and 40 °C.…”

“…Based on both evaluations the chosen in vitro reaction parameters were microsomal fraction equivalent to 0.5 nmol of endogenous PC per assay, a reaction time of 60 min and buffer pH equal to 7.2. The chosen pH corresponds to pH in plant endoplasmic reticulum [ 27 ] and was chosen despite the fact that for in vivo leaves optimal pH value was 9.0 and for seeds the optimal pH value stretched between 9.0 and 10.0 ( Supplementary Figure S1 ; [ 28 ]. We decided to evaluate LPEAT acyl-CoA specificity with 5 substrates: 16:0-CoA, 18:0-CoA, 18:1-CoA, 18:2-CoA, and 18:3-CoA.…”

Phospholipid:Diacylglycerol Acyltransferase1 Overexpression Delays Senescence and Enhances Post-heat and Cold Exposure Fitness

“…The supernatants were disposed of and the obtained pellets (containing microsomal fraction) were suspended in 0.1 M potassium phosphate buffer (pH 7.2). Aliquots of each suspension were used to measure microsomal protein content via Pierce TM BCA Protein Assay Kit (Thermo Fisher Scientific) and analyze phosphatidylcholine (PC) content as previously described by Klińska et al (2019). PC content is equivalent to membrane concentrations in microsomal fractions.…”

Functional Characterization of Lysophosphatidylcholine: Acyl-CoA Acyltransferase Genes From Sunflower (Helianthus annuus L.)

“…Lager et al (2013) studied the forms of At and other species like Lesquerella fendleri, R. communis, Carthamus ticntorius, or Hiptage benghalensis in all cases activities were lower with saturated 16:0-acyl-CoA and higher with unsaturated or polyunsaturated derivatives. A more recent work on C. sativa LPCAT measured in microsomes from developing seeds displayed a similar activity profile (Kliñska et al, 2019). This similarity in the acyl-CoA specificity of LPCATs from different species suggests that LPCAT action is central to maintaining the membrane fluidity and functionality.…”

“…LPCAT can also catalyze the formation of acyl-CoA and LPC from PC and free CoA under certain conditions, in what is known as its reverse reaction (Stymne and Stobart, 1984), which has been shown to display substrate specificities different from the forward reaction (Lager et al, 2013). LPCAT homologs have been investigated in Brassica napus and Camelina sativa (Zheng et al, 2012;Kliñska et al, 2019). Another important role proposed for LPCAT was supplying LPC for the synthesis of plastidial galactolipids (Mongrand et al, 1997(Mongrand et al, , 2000, which is an important aspect of lipid trafficking between the ER and chloroplasts.…”