A dual-specific Glu-tRNA(Gln) and Asp-tRNA(Asn) amidotransferase is involved in decoding glutamine and asparagine codons in Acidithiobacillus ferrooxidans

The gatC, gatA and gatB genes encoding the three subunits of glutamyl-tRNA( Gln) amidotransferase from Acidithiobacillus ferrooxidans, an acidophilic b acterium used in bioleaching of minerals, have been cloned and expressed in Escherichia coli, As in Bacillus subtilis the three fiat genes are organiz ed in an operon-like structure in ii. ferrooxidans, The heterologously over expressed enzyme converts Glu-tRNA(Gln) To Gln-tRNA(Gln) and Asp-tRNA(Asn) to Asn-tRNA(Asn). Biochemical analysis revealed that neither glutaminyl-tRN A synthetase nor asparaginyl-tRNA synthetase is present in A. ferrooxidans, but that glutamyl-tRNA synthetase and aspartyl-tRNA synthetase enzymes are present in the organism, These data suggest that the transamidation pathwa y is responsible for the formation of Gln-tRNA and Asn-tRNA in A. ferrooxid ans. (C) 2001 Published by Elsevier Science B.V. on behalf of the Federatio n of European Biochemical Societies.