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.
Department of Biochemistry, University of Nebraska, Lincoln, NE 68588, USA.
Sergey V
SV
Novoselov
Mahadev
M
Rao
Natalia V
NV
Onoshko
Huijun
H
Zhi
Gregory V
GV
Kryukov
Youbin
Y
Xiang
Donald P
DP
Weeks
Dolph L
DL
Hatfield
Vadim N
VN
Gladyshev
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