Nucleotide sequences of two serine tRNAs with a GGA anticodon: the structure-function relationships in the serine family ofE. colitRNAs

Abstract

We have determined the nucleotide sequence of the major species of E.colitRNA^Ser and of a minor species having the same GGA anticodon. These two tRNAs should recognize the UCC and UCU codons, the most widely used codons for serine in the highly expressed genes of E.coli. The two sequences differ in only one position of the D-loop. Neither tRNA has a modified adenosine in the position 3′-adjacent to the anticodon. This can be rationalized on the basis of a structural constraint in the anticodon stem and may be related to optimization of the codon-anticodon interaction. Conparison of all E.coli serine tRNAs (and that encoded by bacteriophage T₄) reveals characteristic (possibly functional) features. Evolutionary analysis suggests an eubacterial origin of the T₄tRNA^Ser gene and the existences of a recent common ancestor for the and genes.