title: Brevetoxin, the Dinoflagellate Neurotoxin, Localizes to Thylakoid Membranes and Interacts with the Light-Harvesting Complex II (LHCII) of Photosystem II.
abstract: The brevetoxins are neurotoxins that are produced by the "Florida red tide" dinoflagellate Karenia brevis. They bind to and activate the voltage-gated sodium channels in higher organisms, specifically the Nav 1.4 and Nav 1.5 channel subtypes. However, the native physiological function that the brevetoxins perform for K. brevis is unknown. By using fluorescent and photoactivatable derivatives, brevetoxin was shown to localize to the chloroplast of K. brevis where it binds to the light-harvesting complex II (LHCII) and thioredoxin. The LHCII is essential to non-photochemical quenching (NPQ), whereas thioredoxins are critical to the maintenance of redox homeostasis within the chloroplast and contribute to the scavenging of reactive oxygen. A culture of K. brevis producing low levels of toxin was shown to be deficient in NPQ and produced reactive oxygen species at twice the rate of the toxic culture, implicating a role in NPQ for the brevetoxins.
authors.affiliation: Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th St., Miami, FL 33199 (USA).
authors.forename: Ryan T
authors.initials: RT
authors.lastname: Cassell
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Serge
authors.initials: S
authors.lastname: Thomas
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Kathleen S
authors.initials: KS
authors.lastname: Rein
mesh_terms: D001692:Biological Transport; D004141:Dinoflagellida / Q000166:cytology* / Q000378:metabolism*; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism*; D008387:Marine Toxins / Q000378:metabolism*; D009498:Neurotoxins / Q000378:metabolism*; D035964:Oxocins / Q000378:metabolism*; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D011485:Protein Binding; D017382:Reactive Oxygen Species / Q000378:metabolism; D020524:Thylakoids / Q000378:metabolism*; D000095702:Polyether Toxins
chemical_list: D045342:Light-Harvesting Protein Complexes; D008387:Marine Toxins; D009498:Neurotoxins; D035964:Oxocins; D045332:Photosystem II Protein Complex; D017382:Reactive Oxygen Species; C053342:brevetoxin; D000095702:Polyether Toxins
keywords: bioorganic chemistry; brevetoxin; fluorescent probes; photoaffinity labeling