Open AccessThe selenocysteine-inserting opal suppressor serine tRNA fromE.coliis highly unusual in structure and modification
Author(s) -
Astrid Schön,
August Böck,
Günther Ott,
Dieter Söll
Publication year - 1989
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/17.18.7159
Subject(s) - transfer rna , biology , selenocysteine , t arm , gene , genetics , methanococcus , serine , base pair , nucleic acid sequence , genetic code , biochemistry , escherichia coli , rna , enzyme , cysteine
Selenocysteine is cotranslationally incorporated into selenoproteins in a unique pathway involving tRNA mediated suppression of a UGA nonsense codon (1-3). The DNA sequence of the gene for this suppressor tRNA from Escherichia coli predicts unusual features of the gene product (4). We determined the sequence of this serine tRNA (tRNA(UCASer]. It is the longest tRNA (95 nt) known to date with an acceptor stem of 8 base pairs and lacks some of the 'invariant' nucleotides found in other tRNAs. It is the first E. coli tRNA that contains the hypermodified nucleotide i6A, adjacent to the UGA-recognizing anticodon UCA. The implications of the unusual structure and modification of this tRNA on recognition by seryl-tRNA synthetase, by tRNA modifying enzymes, and on codon recognition are discussed.