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EMBO J. 2002 Jul 15;21(14):3681-93.

Selenoproteins and selenocysteine insertion system in the model plant cell system, Chlamydomonas reinhardtii.

Author information

1
Department of Biochemistry, University of Nebraska, Lincoln, NE 68588, USA.

Abstract

Known eukaryotic selenocysteine (Sec)-containing proteins are animal proteins, whereas selenoproteins have not been found in yeast and plants. Surprisingly, we detected selenoproteins in a member of the plant kingdom, Chlamydomonas reinhardtii, and directly identified two of them as phospholipid hydroperoxide glutathione peroxidase and selenoprotein W homologs. Moreover, a selenocysteyl-tRNA was isolated that recognized specifically the Sec codon UGA. Subsequent gene cloning and bioinformatics analyses identified eight additional selenoproteins, including methionine-S-sulfoxide reductase, a selenoprotein specific to Chlamydomonas: Chlamydomonas selenoprotein genes contained selenocysteine insertion sequence (SECIS) elements that were similar, but not identical, to those of animals. These SECIS elements could direct selenoprotein synthesis in mammalian cells, indicating a common origin of plant and animal Sec insertion systems. We found that selenium is required for optimal growth of Chlamydomonas: Finally, evolutionary analyses suggested that selenoproteins present in Chlamydomonas and animals evolved early, and were independently lost in land plants, yeast and some animals.

PMID:
12110581
PMCID:
PMC126117
DOI:
10.1093/emboj/cdf372
[Indexed for MEDLINE]
Free PMC Article

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