Molecular evolution of the lysophosphatidic acid acyltransferase (LPAAT) gene family.

Lysophosphatidic acid acyltransferases (LPAATs) perform an essential cellular function by controlling the production of phosphatidic acid (PA), a key intermediate in the synthesis of membrane, signaling and storage lipids. Although LPAATs have been extensively explored by functional and biotechnological studies, little is known about their molecular evolution and diversification. We performed a genome-wide analysis using data from several plants and animals, as well as other eukaryotic and prokaryotic species, to identify LPAAT genes and analyze their evolutionary history. We used phylogenetic and molecular evolution analysis to test the hypothesis of distinct origins for these genes. The reconstructed phylogeny supported the ancient origin of some isoforms (plant LPAAT1 and LPAATB; animal AGPAAT1/2), while others emerged more recently (plant LPAAT2/3/4/5; AGPAAT3/4/5/8). Additionally, the hypothesis of endosymbiotic origin of the plastidic isoform LPAAT1 was confirmed. LPAAT genes from plants and animals mainly experienced strong purifying selection pressures with limited functional divergence after the species-specific duplications. Gene expression analyses of LPAAT isoforms in model plants demonstrated distinct LPAAT expression patterns in these organisms. The results showed that distinct origins followed by diversification of the LPAAT genes shaped the evolution of TAG biosynthesis. The expression pattern of individual genes may be responsible for adaptation into multiple ecological niches.