title: Characterization of an epoxide hydrolase from the Florida red tide dinoflagellate, Karenia brevis.
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.
authors.affiliation: Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA. Electronic address: psun001@fiu.edu.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Sun
authors.affiliation: Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
authors.forename: Cristian
authors.initials: C
authors.lastname: Leeson
authors.affiliation: Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
authors.forename: Xiaoduo
authors.initials: X
authors.lastname: Zhi
authors.affiliation: Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA. Electronic address: lengf@fiu.edu.
authors.forename: Fenfei
authors.initials: F
authors.lastname: Leng
authors.affiliation: Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL 34236, USA. Electronic address: rich@mote.org.
authors.forename: Richard H
authors.initials: RH
authors.lastname: Pierce
authors.affiliation: Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL 34236, USA. Electronic address: mhenry@mote.org.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Henry
authors.affiliation: Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA. Electronic address: reink@fiu.edu.
authors.forename: Kathleen S
authors.initials: KS
authors.lastname: Rein
mesh_terms: D004141:Dinoflagellida / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D004851:Epoxide Hydrolases / Q000378:metabolism*; D004852:Epoxy Compounds / Q000737:chemistry; D005431:Florida; D057097:Harmful Algal Bloom; D008387:Marine Toxins / Q000378:metabolism*; D008970:Molecular Weight; D035964:Oxocins / Q000378:metabolism*; D000095702:Polyether Toxins
chemical_list: D004851:Epoxide Hydrolases; D004852:Epoxy Compounds; D008387:Marine Toxins; D035964:Oxocins; C053342:brevetoxin; D000095702:Polyether Toxins; C043134:leukotriene A4 hydrolase
keywords: Brevetoxin; Dinoflagellate; Dinophyceae; Epoxide hydrolase; Karenia brevis; Prorocentrum hoffmanianum; Protein biochemistry