Physaria fendleri and Ricinus communis LCAT-like phospholipases selectively cleave hydroxy acyl chains from phosphatidylcholine
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Xu, Y., Caldo, K. M. P., Singer, S. D., Mietkiewska, E., Greer, M. S., Tian, B., ... & Weselake, R. J. (2020). Physaria fendleri and Ricinus communis LCATālike phospholipases selectively cleave hydroxy acyl chains from phosphatidylcholine. The Plant Journal. https://doi.org/10.1111/tpj.15050
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Abstract
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Producing hydroxy fatty acids (HFAs) in transgenic crops represents a promising strategy to meet our
demands for specialized plant oils with industrial applications. The expression of Ricinus communis
(castor) OLEATE 12-HYDROXYLASE (RcFAH12) in Arabidopsis has resulted in only limited
accumulation of HFA in seeds, which likely results from inefficient transfer of HFAs from their site
of synthesis (phosphatidylcholine; PC) to triacylglycerol (TAG), especially at the sn-1/3 positions of
TAG. Phospholipase As (PLAs) may be directly involved in the liberation of HFAs from PC, but the
functions of their over-expression in HFA accumulation and distribution at TAG in transgenic plants
have not been well-studied. In this study, the functions of lecithin:cholesterol acyltransferase-like
PLAs (LCAT-PLAs) in HFA biosynthesis were characterized. LCAT-PLAs were shown to exhibit
homology to LCAT and mammalian lysosomal PLA2, and to contain a conserved and functional
Ser/His/Asp catalytic triad. In-vitro assays revealed that LCAT-PLAs from HFA-accumulating plant
species Physaria fendleri (PfLCAT-PLA) and castor (RcLCAT-PLA) could cleave acyl chains at both
the sn-1 and sn-2 positions of PC, and displayed substrate selectivity towards sn-2-ricinoleoyl-PC
over sn-2-oleoyl-PC. Furthermore,co-expression of RcFAH12 with PfLCAT-PLA or RcLCAT-PLA,
but not Arabidopsis AtLCAT-PLA, resulted in increased HFA occupation at the sn-1/3 positions of
TAG as well as small but insignificant increases in HFA levels in Arabidopsis seeds compared to
RcFAH12 expression alone. Therefore, PfLCAT-PLA and RcLCAT-PLA may contribute to HFA
turnover on PC, and represent potential candidates for engineering unusual fatty acid production in
crops.
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http://purl.org/coar/resource_type/c_6501 http://purl.org/coar/version/c_b1a7d7d4d402bcce http://purl.org/coar/version/c_71e4c1898caa6e32
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