Characterization of two <it>Arabidopsis thaliana </it>acyltransferases with preference for lysophosphatidylethanolamine

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<p>Abstract</p> <p>Background</p> <p>Two previously uncharacterized Arabidopsis genes that encode proteins with acyltransferase PlsC regions were selected for study based on their sequence similarity to a recently identified lung lysophosphatidylcholine acyltransferase (LPCAT). To identify their substrate specificity and biochemical properties, the two Arabidopsis acyltransferases, designated AtLPEAT1, (At1g80950), and AtLPEAT2 (At2g45670) were expressed in yeast knockout lines <it>ale1 </it>and <it>slc1 </it>that are deficient in microsomal lysophosphatidyl acyltransferase activities.</p> <p>Results</p> <p>Expression of AtLPEAT1 in the yeast knockout <it>ale1 </it>background exhibited strong acylation activity of lysophosphatidylethanolamine (LPE) and lysophosphatidate (LPA) with lower activity on lysophosphatidylcholine (LPC) and lysophosphatidylserine (LPS). AtLPEAT2 had specificities in the order of LPE > LPC > LPS and had no or very low activity with LPA. Both acyltransferases preferred 18:1-LPE over 16:0-LPE as acceptor and preferred palmitoyl-CoA as acyl donor in combination with 18:1-LPE. Both acyltransferases showed no or minor responses to Ca²⁺, despite the presence of a calcium binding EF-hand region in AtLPEAT2. AtLPEAT1 was more active at basic pH while AtLPEAT2 was equally active between pH 6.0 – 9.0.</p> <p>Conclusion</p> <p>This study represents the first description of plant acyltransferases with a preference for LPE. In conclusion it is suggested that the two AtLPEATs, with their different biochemical and expression properties, have different roles in membrane metabolism/homoeostasis.</p>