Characterization of an epoxide hydrolase from the Florida red tide dinoflagellate, Karenia brevis

Phytochemistry. 2016 Feb;122:11-21. doi: 10.1016/j.phytochem.2015.11.002. Epub 2015 Nov 25.

Abstract

Epoxide hydrolases (EH, EC 3.3.2.3) have been proposed to be key enzymes in the biosynthesis of polyether (PE) ladder compounds such as the brevetoxins which are produced by the dinoflagellate Karenia brevis. These enzymes have the potential to catalyze kinetically disfavored endo-tet cyclization reactions. Data mining of K. brevis transcriptome libraries revealed two classes of epoxide hydrolases: microsomal and leukotriene A4 (LTA4) hydrolases. A microsomal EH was cloned and expressed for characterization. The enzyme is a monomeric protein with molecular weight 44kDa. Kinetic parameters were evaluated using a variety of epoxide substrates to assess substrate selectivity and enantioselectivity, as well as its potential to catalyze the critical endo-tet cyclization of epoxy alcohols. Monitoring of EH activity in high and low toxin producing cultures of K. brevis over a three week period showed consistently higher activity in the high toxin producing culture implicating the involvement of one or more EH in brevetoxin biosynthesis.

Keywords: Brevetoxin; Dinoflagellate; Dinophyceae; Epoxide hydrolase; Karenia brevis; Prorocentrum hoffmanianum; Protein biochemistry.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Dinoflagellida / chemistry
  • Dinoflagellida / enzymology*
  • Dinoflagellida / genetics
  • Epoxide Hydrolases / metabolism*
  • Epoxy Compounds / chemistry
  • Florida
  • Harmful Algal Bloom
  • Marine Toxins / metabolism*
  • Molecular Weight
  • Oxocins / metabolism*

Substances

  • Epoxy Compounds
  • Marine Toxins
  • Oxocins
  • brevetoxin
  • Epoxide Hydrolases
  • leukotriene A4 hydrolase