@article{4cb7169157be4b4a967959818a931237,
title = "SxtA localizes to chloroplasts and changes to its 3′UTR may reduce toxin biosynthesis in non-toxic Alexandrium catenella (Group I)✰",
abstract = "SxtA is the enzyme that catalyses the first step of saxitoxin biosynthesis. We developed an immunofluorescent method to detect SxtA using antibodies against SxtA peptides. Confocal microscopy revealed the presence of abundant, sub-cellularly localized signal in cells of toxic species and its absence in non-toxic species. Co-localization of SxtA with Rubisco II and ultra-structural observation by transmission electron microscopy strongly suggested the association of SxtA with chloroplasts. We also characterized a non-toxic sub-clone of Alexandrium catenella (Group I) to elucidate the mutation responsible for its loss of toxicity. Although sxtA4 gene copy number was indistinguishable in toxic and non-toxic sub-clones, mRNA and protein expression were significantly reduced in the non-toxic sub-clone and we uncovered sequence variation at the 3′ untranslated region (3′UTR) of sxtA4 mRNA. We propose that differences in the sxtA4 mRNA 3′UTR lead to down-regulation of STX biosynthesis post-transcriptionally, thereby explaining the differences in toxicity amongst different A. catenella (Group I) sub-clones.",
keywords = "3′UTR, Biosynthesis, Chloroplast, Dinoflagellate, Localization, Saxitoxin",
author = "Yuko Cho and Shizu Hidema and Takuo Omura and Kazuhiko Koike and Kanae Koike and Hiroshi Oikawa and Keiichi Konoki and Yasukatsu Oshima and Mari Yotsu-Yamashita",
note = "Funding Information: This work was funded by the Japan Society for the Promotion of Science ( JSPS ) through its KAKENHI Grant-in-Aid for Scientific Research no. JP20H02921 to M.Y.Y. and JP19K06232 to Y.C.; by an Innovative Area Frontier Research on Chemical Communications grant (no. JP17H06406 to M.Y.Y.) and Redesigning Biosynthetic Machineries grants (no. JP19H04636 to M.Y.Y. and no. JP17H05426 to Y.C.); and by a Grant-in-Aid for Challenging Exploratory Research (no. JP19K22266 ) to M.Y.Y. We thank Dr. T. Ishimaru of Tokyo University of Marine Science and Technology, who kindly donated the A. catenella (Group I) clonal culture strains Axat-2 and UAT-014–009. We thank Dr. J. Hidema of Tohoku University for his kind advice on immunostaining. We also thank the center of Research Instruments, Institute of Development, Aging and Cancer, Tohoku University for use of high speed confocal platform, Dragonfly500. Funding Information: This work was funded by the Japan Society for the Promotion of Science (JSPS) through its KAKENHI Grant-in-Aid for Scientific Research no. JP20H02921 to M.Y.Y. and JP19K06232 to Y.C.; by an Innovative Area Frontier Research on Chemical Communications grant (no. JP17H06406 to M.Y.Y.) and Redesigning Biosynthetic Machineries grants (no. JP19H04636 to M.Y.Y. and no. JP17H05426 to Y.C.); and by a Grant-in-Aid for Challenging Exploratory Research (no. JP19K22266) to M.Y.Y. We thank Dr. T. Ishimaru of Tokyo University of Marine Science and Technology, who kindly donated the A. catenella (Group I) clonal culture strains Axat-2 and UAT-014–009. We thank Dr. J. Hidema of Tohoku University for his kind advice on immunostaining. We also thank the center of Research Instruments, Institute of Development, Aging and Cancer, Tohoku University for use of high speed confocal platform, Dragonfly500. Publisher Copyright: {\textcopyright} 2020 Elsevier B.V.",
year = "2021",
month = jan,
doi = "10.1016/j.hal.2020.101972",
language = "English",
volume = "101",
journal = "Harmful Algae",
issn = "1568-9883",
publisher = "Elsevier",
}