Physaria fendleri and Ricinus communis LCAT-like phospholipases selectively cleave hydroxy acyl chains from phosphatidylcholine

• Author(s) / Creator(s)

  • Xu, Yang
  • Caldo, Kristian Mark P.
  • Singer, Stacy D.
  • Mietkiewska, Elzbieta
  • Greer, Michael S.
  • Tian, Bo
  • Dyer, John M.
  • Smith, Mark
  • Zhou, Xue-Rong
  • Qiu, Xiao
  • Weselake, Randall J.
  • Chen, Guanqun

• 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.

• Date created

  2020-10-27

• Subjects / Keywords

  • Arabidopsis thaliana
  • Physaria fendleri
  • Phospholipase A
  • Lecithin:cholesterol acyltransferase-like PLA
  • Hydroxy fatty acid
  • Ricinus communis
  • Phosphatidycholine
  • Triacylglycerol

• Type of Item

  Article (Draft / Submitted)

• DOI

  https://doi.org/10.7939/r3-jgpz-r958

• License

  Attribution-NonCommercial 4.0 International