Diatoms and Plants Acyl-CoA:lysophosphatidylcholine Acyltransferases (LPCATs) Exhibit Diverse Substrate Specificity and Biochemical Properties

Abstract

The search of the Phaeodactylum tricornutum genome database revealed the existence of six genes potentially encoding lysophospholipid acyltransferases. One of these genes, Phatr3_J20460, after introduction to yeast ale1 mutant disrupted in the LPCAT gene, produced a very active acyl-CoA:lysophosphatidylcholine (LPCAT) enzyme. Using in vitro assays applying different radioactive and non-radioactive substrates and microsomal fractions from such yeast, we have characterized the biochemical properties and substrate specificities of this PtLPCAT1. We have found that the substrate specificity of this enzyme indicates that it can completely supply phosphatidylcholine (PC) with all fatty acids connected with a biosynthetic pathway of very long-chain polyunsaturated fatty acids (VLC-PUFAs) used further for the desaturation process. Additionally, we have shown that biochemical properties of the PtLPCAT1 in comparison to plant LPCATs are in some cases similar (such as the dependency of its activity on pH value), differ moderately (such as in response to temperature changes), or express completely different properties (such as in reaction to calcium and magnesium ions or toward some acyl-CoA with 20C polyunsaturated fatty acids). Moreover, the obtained results suggest that cloned “Phatr3_J20460” gene can be useful in oilseeds plant engineering toward efficient production of VLC-PUFA as LPCAT it encodes can (contrary to plant LPCATs) introduce 20:4-CoA (n-3) to PC for further desaturation to 20:5 (EPA, eicosapentaenoic acid).

Physiochemical and molecular responses of the diatom Phaeodactylum tricornutum to illumination transitions

“…8 ), probably providing PC for PDAT (utilizing PC as the acyl donor for TAG synthesis) to support the increase of TAG. It has been demonstrated that LPCAT utilizes the cytosolic acyl-CoA pool and lysophospholipids to regenerate PC and PE [ 60 ]. When the HL stress was removed, while many polar lipid synthetic genes did not or slightly recovered, several ones recovered considerably, including MDG (Phatr3_J54168), and PGPS (Fig.…”

Biochemical characterization of acyl-CoA:diacylglycerol acyltransferase2 from the diatom Phaeodactylum tricornutum and its potential effect on LC-PUFAs biosynthesis in planta

“…tricorunutum culturing temperature, which is 19 o C [ 8 , 41 ]. Nevertheless, this enzyme also maintained a quite high activity at 20 o C reaching 79% of maximum activity at 30 o C. The disparity between the native temperature environment of an enzyme and its biochemical properties is a common characteristic among acyltransferases [ 33 , 42 , 43 ]. We cannot exclude, that observed discrepancies result from membrane composition differences between native membrane of diatom and yeast, in which their activity was tested.…”

Pan-cancer analysis identifies LPCATs family as a prognostic biomarker and validation of LPCAT4/WNT/β-catenin/c-JUN/ACSL3 in hepatocellular carcinoma

“…The lysophosphatidylcholine acyltransferases (LPCATs) family contains four members, namely LPCAT1-4 [ 9 ]. LPCATs are crucial in lipid metabolism since they allow for the production of novel phospholipid molecules in a way that is separate from de novo synthesis [ 10 ].…”