title: The central role of selenium in the biochemistry and ecology of the harmful pelagophyte, Aureococcus anophagefferens.
abstract: The trace element selenium (Se) is required for the biosynthesis of selenocysteine (Sec), the 21st amino acid in the genetic code, but its role in the ecology of harmful algal blooms (HABs) is unknown. Here, we examined the role of Se in the biology and ecology of the harmful pelagophyte, Aureococcus anophagefferens, through cell culture, genomic analyses, and ecosystem studies. This organism has the largest and the most diverse selenoproteome identified to date that consists of at least 59 selenoproteins, including known eukaryotic selenoproteins, selenoproteins previously only detected in bacteria, and novel selenoproteins. The A. anophagefferens selenoproteome was dominated by the thioredoxin fold proteins and oxidoreductase functions were assigned to the majority of detected selenoproteins. Insertion of Sec in these proteins was supported by a unique Sec insertion sequence. Se was required for the growth of A. anophagefferens as cultures grew maximally at nanomolar Se concentrations. In a coastal ecosystem, dissolved Se concentrations were elevated before and after A. anophagefferens blooms, but were reduced by >95% during the peak of blooms to 0.05 nM. Consistent with this pattern, enrichment of seawater with selenite before and after a bloom did not affect the growth of A. anophagefferens, but enrichment during the peak of the bloom significantly increased population growth rates. These findings demonstrate that Se inventories, which can be anthropogenically enriched, can support proliferation of HABs, such as A. anophagefferens through its synthesis of a large arsenal of Se-dependent oxidoreductases that fine-tune cellular redox homeostasis.
authors: School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794-5000, USA. Christopher.Gobler@stonybrook.edu
authors: Christopher J
authors: CJ
authors: Gobler
authors: Alexei V
authors: AV
authors: Lobanov
authors: Ying-Zhong
authors: YZ
authors: Tang
authors: Anton A
authors: AA
authors: Turanov
authors: Yan
authors: Y
authors: Zhang
authors: Martina
authors: M
authors: Doblin
authors: Gordon T
authors: GT
authors: Taylor
authors: Sergio A
authors: SA
authors: Sañudo-Wilhelmy
authors: Igor V
authors: IV
authors: Grigoriev
authors: Vadim N
authors: VN
authors: Gladyshev
mesh_terms: D001671:Biochemistry; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000378:metabolism; D004251:DNA Transposable Elements / Q000235:genetics; D004463:Ecology; D017125:Genes, Protozoan / Q000235:genetics; D020543:Proteome; D012623:Seawater / Q000469:parasitology*; D012643:Selenium / Q000378:metabolism* / Q000494:pharmacology; D051140:Selenoproteins / Q000235:genetics* / Q000378:metabolism*; D058009:Stramenopiles / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D014131:Trace Elements / Q000494:pharmacology
chemical_list: D004251:DNA Transposable Elements; D020543:Proteome; D051140:Selenoproteins; D014131:Trace Elements; D012643:Selenium