Selenoproteins and selenocysteine insertion system in the model plant cell system, Chlamydomonas reinhardtii.
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.
Novoselov
Sergey V
SV
Department of Biochemistry, University of Nebraska, Lincoln, NE 68588, USA.
Rao
Mahadev
M
Onoshko
Natalia V
NV
Zhi
Huijun
H
Kryukov
Gregory V
GV
Xiang
Youbin
Y
Weeks
Donald P
DP
Hatfield
Dolph L
DL
Gladyshev
Vadim N
VN
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016825:Chlamydomonas reinhardtii / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005979:Glutathione Peroxidase / Q000378:metabolism; D006801:Humans; D008954:Models, Biological; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D018749:RNA, Plant / Q000737:chemistry / Q000235:genetics; D017279:Selenocysteine / Q000378:metabolism*; D051151:Selenoprotein W; D051140:Selenoproteins; D017386:Sequence Homology, Amino Acid
D011506:Proteins; D018749:RNA, Plant; C495240:SELENOW protein, human; D051151:Selenoprotein W; D051140:Selenoproteins; D017279:Selenocysteine; D005979:Glutathione Peroxidase