Evolutionary and biochemical characterization of a Chromochloris zofingiensis MBOAT with wax synthase and DGAT activity

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  • Abstract:
    Wax synthase (WS) catalyzes the last step in wax ester biosynthesis in green plants. Two unrelated subfamilies of WS including the bifunctional acyltransferase and plant-like WS have been reported, but the latter is largely uncharacterized in microalgae. Here, we functionally characterized a putative plant-like WS from the emerging model green microalga Chromochloris zofingiensis (CzWS1). Our results showed that plant-like WS evolved under different selection constraints in plants and microalgae, with positive selection likely contributing to functional divergence. Unlike jojoba with high amounts of wax ester in seeds and a highly active WS enzyme, C. zofingiensis has no detectable wax ester but high abundance of WS transcripts. Co-expression analysis showed that C. zofingiensis WS has different expression correlations with lipid biosynthetic genes from jojoba and may have a divergent function. In vitro characterization indicated CzWS1 had diacylglycerol acyltransferase activity along with WS activity and overexpression of CzWS1 in yeast and Chlamydomonas reinhardtii affected triacylglycerol accumulation in yeast and microalgal cells. Moreover, biochemical and bioinformatic analyses revealed the relevance of the C-terminal region of CzWS1 in enzyme function. Taken together, our results indicated functional divergence of plant-like WS in plants and microalgae and the importance of C-terminal region in enzyme functional specialization.

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    Article (Published)
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    Attribution-NonCommercial 4.0 International
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    • Xu, Y., Pan, X., Lu, J., Wang, J., Shan, Q., Stout, J., & Chen, G. (2021). Evolutionary and biochemical characterization of a Chromochloris zofingiensis MBOAT with wax synthase and diacylglycerol acyltransferase activity. Journal of Experimental Botany, 72(15), 5584–5598. https://doi.org/10.1093/jxb/erab236
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    This article has been accepted for publication in the Journal of Experimental Botany Published by Oxford University Press.
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