FIGURE 1.

Using sequence conservation to direct the mutagenesis of nine base pairs and three base triples in the anticodon hairpin and tertiary core of E. coli tRNA^Ala_GGC (blue). The bar graphs compare the frequency of different 12-23-9 base triple sequences (left) and 31-39 base pair sequences (right) present among 97 bacterial tRNA^Ala_GGC (gray bars) with the corresponding sequences present among 3623 bacterial tRNAs of the D4V5 structural class (black bars). Nonconsensus mutations of E. coli tRNA^Ala_GGC (red arrows) are not present in any bacteria tRNA^Ala_GGC but are used in other tRNAs. Consensus mutations (green arrows) are present in tRNA^Ala_GGC from other species. Sequence conservation data and mutations chosen for all the base pairs and triples are in Table 1.