FIG. 2.
dnaX, encoding both the τ and γ subunits of the DNA polymerase III holoenzyme, is the only intact gene within the overlapping genomic regions of the suppressor clones. (A) Shown in the top bar are all known genes (shaded boxes) and open reading frames (black and hatched boxes) that lie within the region potentially contained within the suppressor clones (nucleotides 4.87 × 105 to 5.01 × 105 of the E. coli chromosome). The genomic regions contained on suppressor clones 31, 37, and 39 are shown below. (B) dnaX open reading frame with an exploded view of the region where the ribosomal frameshifting event that generates the γ subunit (codons 428 to 430) occurs. Also indicated is the AflII restriction endonuclease site used to generate the dnaX open reading frame disruption. aa, amino acids.