Figure 1

a. The physical map of the thy A- arg A region of the E. coli K-12 chromosome, and the nucleotide sequence of the rec B- rec D overlap site where rec BD fusion mutations were constructed. The nucleotide A that overlaps the stop codon rec B (TAA) and the start codon rec D (atg) is shown in the square. rec B nucleotides are depicted in capital letters while rec D nucleotides are depicted in small letters in order to distinguish them. b. The sequence analysis results of the deletion (top) and substitution (bottom) fusion mutations after mutagenesis by recombineering.