Figure 1.

Description of the defective λ prophage on the E. coli chromosome. The defective prophage contains λ genes from cI to int. A deletion (dotted line) removes the right side of the prophage from cro through attR and including bioA (21). On the chromosome, the nadA and gal operons are to the left of the prophage, and the bio genes without bioA are to the right. Genes of the λ prophage are shown on the solid line, and genes of the host are shown on the broken line. p_L and p_R indicate the early left and right promoters of λ. attL and attR indicate the left and right attachment sites of λ. The λ genes and functions have been described (17).