Fig. 1

Structure of the lactose operon and sequence alignment. For lactose operon, the 212 bp deletion and a single base insertion of E. coli K-12 GM4792 are illustrated. Regarding the sequences, only the mutation region is displayed. The sequences of all white clones are identical to lac-(ancestor). Conversely, all blue clones carry nucleotide deletions, which are confined to the region (indicated by horizontal stripes) between the single base insertion site 958 of the lacI gene and the lacZ gene. For convenience, we have also included the corresponding fragment sequences of E. coli K-12 MG1655