Clustered arg genes on a BamHI. Segment of the Escherichia coli chromosome

BamHI cleavage of DNAs from transducing phages λd arg13 ( ppc, argECBH, bfe), λd arg14: ( ppc, argECBH) and λd arg23 ( argECBH) yields three purely λ DNA segments (and, in one case, a fourth), as well as several Escherichia coli-DNA-containing segments. The length (in kilobases, kb) of the segments, determined by electron microscopy and agarose gel electrophoresis is 4.2, 7.5, 8.4, 6.2, 6.9, and 6.4 kb for λ darg13; 13.0, 7.5, 4.7, 6.2, 6.9, and 6.4 kb for λd arg14: and 5.3, 11.0, 4.7, 6.2, 6.9, and 6.4 kb for λd arg23. Ordering of the segments (in relation to the λ genetic map and with the direction from left to right corresponding to the clockwise orientation of the E. coli genetic map and to each of the numerical sequences given) reveals, on 26 kb of bacterial DNA, two cleavage sites defining the 7.5-kb segment obtainable from the DNA of either λ darg13 or λd arg14. These and analogous findings with argEC and argCB deletion-bearing strains, together with results from heteroduplex experiments, locate argE, argC, argB, and presumably argH on the 7.5-kb segment.