Essential components of the xanthophyll cycle differ in high and low toxin Karenia brevis

• Published in: Harmful algae Vol. 103; p. 102006
• Main Authors: Colon, Ricardo, Rein, Kathleen S
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.03.2021
• Subjects: Diadinoxanthin; Dinoflagellida; Gulf of Mexico; Karenia brevis; MGDG; Neurotoxins; Photosystem II Protein Complex; Redox proteomics; Thioredoxin system; Xanthophyll cycle; Xanthophylls; Gulf of Mexico; Diadinoxanthin; MGDG; Redox proteomics; Thioredoxin system; Xanthophyll cycle; Karenia brevis
• ISSN: 1568-9883; 1878-1470
• DOI: 10.1016/j.hal.2021.102006

•Karenia brevis strains with a 10 fold difference in toxin content were compared.•Proteins from a low toxin strain show a 25% increase in reduced cysteine.•The enzymes Dde, MGDG synthase and Trx are more reduced in low toxin cultures.•K. brevis with low toxin quota produces twice the MGDG when normalized to protein. The dinoflagellate Karenia brevis, blooms annually in the Gulf of Mexico, producing a suite of neurotoxins known as the brevetoxins. The cellular toxin content of K. brevis, however, is highly variable between or even within strains. Herein, we investigate physiological differences between high (KbHT) and low (KbLT) toxin producing cultures both derived from the Wilson strain, related to energy-dependent quenching (qE) by photosystem II, and reduced thiol content of the proteome. We demonstrate that gene and protein expression of the xanthophyll cycle enzyme diadinoxanthin de-epoxidase (Dde) and monogalactosyldiacylglycerol (MGDG) synthase are not significantly different in the two cultures. Using redox proteomics, we report a significantly higher reduced cysteine content in the low toxin proteome, including plastid localized thioredoxin reductase (Trx) which can result in inactivation of Dde and activation of MGDG synthase. We also report significant differences in the lipidomes of KbHT and KbLT with respect to MGDG, which facilitates the xanthophyll cycle.