Acyl-CoA:Lysophosphatidylethanolamine Acyltransferase Activity Regulates Growth of Arabidopsis

Abstract

Arabidopsis () contains two enzymes (encoded by the and genes) preferentially acylating lysophosphatidylethanolamine (LPE) with acyl-coenzyme A (CoA), designated LYSOPHOSPHATIDYLETHANOLAMINE ACYLTRANSFERASE1 (LPEAT1) and LPEAT2. The transfer DNA insertion mutant lpeat2 and the double mutant lpeat1 lpeat2 showed impaired growth, smaller leaves, shorter roots, less seed setting, and reduced lipid content per fresh weight in roots and seeds and large increases in LPE and lysophosphatidylcholine (LPC) contents in leaves. Microsomal preparations from leaves of these mutants showed around 70% decrease in acylation activity of LPE with 16:0-CoA compared with wild-type membranes, whereas the acylation with 18:1-CoA was much less affected, demonstrating that other lysophospholipid acyltransferases than the two LPEATs could acylate LPE The above-mentioned effects were less pronounced in the single lpeat1 mutant. Overexpression of either LPEAT1 or LPEAT2 under the control of the 35S promotor led to morphological changes opposite to what was seen in the transfer DNA mutants. Acyl specificity studies showed that LPEAT1 utilized 16:0-CoA at the highest rate of 11 tested acyl-CoAs, whereas LPEAT2 utilized 20:0-CoA as the best acyl donor. Both LPEATs could acylate either position of ether analogs of LPC The data show that the activities of LPEAT1 and LPEAT2 are, in a complementary way, involved in growth regulation in Arabidopsis. It is shown that LPEAT activity (especially LPEAT2) is essential for maintaining adequate levels of phosphatidylethanolamine, LPE, and LPC in the cells.

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

“…It was suggested, that PE-producing LPEAT enzymes may be connected with the regulation of the autophagy intensity ( Jasieniecka-Gazarkiewicz et al, 2017 ). We decided to test, whether PDAT1 overexpression or knockout would trigger increase or decrease in autophagocytic response, since PE is a major substrate for PDAT.…”

“…For conducting enzyme assays we have utilized substrates both employed by the enzymes and with proven in vitro activity ( Ståhl et al, 2004 ; Banaś et al, 2014 ; Jasieniecka-Gazarkiewicz et al, 2017 ). For LPCAT activity tests, following optimization, 5 nmol of exogenous sn-1-18:1-lysophosphatidylcholine and 5 nmol of exogenous [ 14 C]18:2-CoA were used with aliquots of microsomal fractions equivalent to 0.05 nmol (both roots and rosettes) of endogenous PC (0.022 μg of microsomal protein).…”

The Lipid Flippases ALA4 and ALA5 Play Critical Roles in Cell Expansion and Plant Growth

“…It is also noteworthy that the loss of ALA6/7 (from cluster 3) results in pollen grains with a similar ~2-fold increase in PA (McDowell et al, 2015), indicating a consistent link between the ALA4/5/6/7 clade of flippases and the regulation of PA homeostasis. The small increase in LysoPE, a monoacyl PE molecule, can also be from multiple causes, including increased phospholipase A (PLA) activity removing a fatty acid from the sn-2 position of the PE glycerol backbone (Bahn et al, 2003), or a decrease in the conversion of LysoPE to PE via LysoPE acyltransferases (LPEATs) (Jasieniecka-Gazarkiewicz et al, 2017). LysoPE also has connections to growth signaling, as mutants deficient in LPEATs display LysoPE accumulation and growth inhibition.…”

Identification and analysis of oil candidate genes revealed the molecular basis of oil accumulation in Gossypium hirsutum L. for cottonseed biofuels development

“…Moreover, HSL1dependent histone methylation plays critical roles in regulation of seed dormancy during seed germination and early seedling growth, which will affect the oil content accumulated in seed [53]. Similarly, AtLPEAT2 [54], AtLACS2 [55] and ChACP4 [56] were found to be associated with PI (34:3), linolenic acid (P = 2.63e-07), and pyruvate (LOD = 14.68) in oil synthesis process, respectively. Ma et al [39] also found that the cotton genes GhHSL1, GhACP2 and GhLPEAT2 were differentially expressed between the upland cotton (G. hirsutum L.) high oil content genotype (3008) and low oil content genotype (3012) in 10, 20 and 30 DPA ovules.…”