FIG. 1.

Gene organization of the E. coli eut operon and insert DNA of plasmids used in this study. The map is drawn to scale. Genes are indicated by boxes. The DNA regions carried by mutant plasmids are shown with thick bars below the map. Dotted lines indicate deletions. The eutB and eutC genes encode the α- and β-subunits of EAL, respectively. The restriction enzymes used for the construction of deletion mutants are HindIII/BsmI for pUCEA3d1, SmaI for pUCEA3d2, AatII/NheI for pUCEA3d3, SalI/EcoRV for pUCEA3d4, RsrII/ScaI for pUCEA3d5, DraI/SacII for pUCEA3d6, and AatII/PstI for pUCEA3d7.