Selenoprotein synthesis in archaea.
The availability of the genome sequences from several archaea has facilitated the identification of the encoded selenoproteins and also of most of the components of the machinery for selenocysteine biosynthesis and insertion. Until now, selenoproteins have been identified solely in species of the genera Methanococcus (M.) and Methanopyrus. Apart from selenophosphate synthetase, they include only enzymes with a function in energy metabolism. Like in bacteria and eukarya, selenocysteine insertion is directed by a UGA codon in the mRNA and involves the action of a specific tRNA and of selenophosphate as the selenium donor. Major differences to the bacterial system, however, are that no homolog for the bacterial selenocysteine synthase was found and, especially, that the SECIS element of the mRNA is positioned in the 3' nontranslated region. The characterisation of a homolog for the bacterial SelB protein showed that it does not bind to the SECIS element necessitating the activity of at least a second protein. The use of the genetic system of M. maripaludis allowed the heterologous expression of a selenoprotein gene from M. jannaschii and will facilitate the elucidation of the mechanism of the selenocysteine insertion process in the future.
Rother
M
M
Lehrstuhl für Mikrobiologie der Universität München, Institut für Genetik und Mikrobiologie, Maria Ward Stra section signe 1a, D-80638 Munich, Germany.
Resch
A
A
Wilting
R
R
Böck
A
A
D000595:Amino Acid Sequence; D001105:Archaea / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D003062:Codon; D017017:Methanococcus / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010445:Peptide Elongation Factors / Q000737:chemistry / Q000378:metabolism; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics*; D019642:RNA, Archaeal / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017279:Selenocysteine / Q000378:metabolism*; D051140:Selenoproteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D003062:Codon; D010445:Peptide Elongation Factors; D011506:Proteins; D019642:RNA, Archaeal; D012333:RNA, Messenger; D051140:Selenoproteins; D017279:Selenocysteine