COEXPRESSION OF EUKARYOTIC TRNA(SER) AND YEAST SERYL-TRANSFER-RNA SYNTHETASE LEADS TO FUNCTIONAL AMBER SUPPRESSION IN ESCHERICHIA-COLI

In order to gain insight into the conservation of determinants for tRN A identity between organisms, Schizosaccharomyces pombe and human ambe r suppressor serine tRNA genes have been examined for functional expre ssion in Escherichia coli. The primary transcripts, which originated f rom E. coli plasmid promoters, were processed into mature tRNAs, but t hey were poorly aminoacylated in E. coli and thus were nonfunctional a s suppressors in vivo. However, coexpression of cloned Saccharomyces c erevisiae seryl-tRNA synthetase led to efficient suppression in E. col i. This shows that some, but not all, determinants specifying the tRNA (Ser) identity are conserved in evolution.