Open AccessSelenocysteine inserting tRNAs: an overview
Author(s) -
Commans Stephane,
Böck August
Publication year - 1999
Publication title -
fems microbiology reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.91
H-Index - 212
eISSN - 1574-6976
pISSN - 0168-6445
DOI - 10.1111/j.1574-6976.1999.tb00403.x
Subject(s) - selenocysteine , transfer rna , biology , amino acid , selenoprotein , biosynthesis , amino acyl trna synthetases , serine , biochemistry , gene , genetics , rna , cysteine , enzyme , glutathione , glutathione peroxidase
One of the recent discoveries in protein biosynthesis was the finding that selenocysteine, the 21st amino acid, is cotranslationally inserted into polypeptides under the direction of a UGA codon assisted by a specific structural signal in the mRNA. The key to selenocysteine biosynthesis and insertion is a special tRNA species, tRNA Sec . The formation of selenocysteine from serine represents an interesting tRNA‐mediated amino acid transformation. tRNA Sec (or the gene encoding it) has been found over all three domains of life. It displays a number of unique features that designate it a selenocysteine‐inserting tRNA and differentiate it from canonical elongator tRNAs. Although there are still some uncertainties concerning the precise secondary and tertiary structures of eukaryal tRNA Sec , the major identity determinant for selenocysteine biosynthesis and insertion appears to be the 13 bp long extended acceptor arm. In addition the core of the 3D structure of these tRNAs is different from that of class II tRNAs like tRNA Ser . The biological implications of these structural differences still remain to be fully understood.