EcoRI cleavage sites in the argECBH region of the Escherichia coli chromosome.

The EcoRI cleavage of deoxyribonucleic acids (DNAs) from lambdadarg phages, carrying argECBH, has been examined. The phages are derived from the heat-inducible, lysis-defective strain lambda y199, and their bacterial DNA, including argECBH, is derived from Escherichia coli K-12. Such cleavage of the phage DNAs, in each case, produces the D, E, and F segments of lambda. Additionally, these DNAs yield segments, ordered from left to right, of length (in kilobases [kb]) determined by electron microscopy and 0.7% agarose slab gel electrophoresis as follows: lambdadarg13 (ppc argECBH bfe), 13.9, 2.8, 1.5, and 5.6; lambdadarg14 (ppc argECBH), 3.0, 2.0, 17.3, and 6.2; and lambdadarg23 (argECBH), 18.4 and 6.2. For lambdadarg13 sup102 DNA, the segment analogous to the 13.9-kb segment measures 12.2 kb. The direction from left to right corresponds to the clockwise orientation of the E. coli genetic map. The EcoRI segments define five cleavage sites near the arg region of the E. coli chromosome. For each of the DNAs, the arg genes occur on the largest segment produced. The 17.3-kb segment, being entirely bacterial, represents the argECBH-bearing EcoRI segment of the E. coli chromosome. The location of the arg genes was demonstrated electron microscopically in heteroduplex experiments.