RELATIONSHIPS BETWEEN THE PHYSICAL AND GENETIC MAPS OF A 470X10(3) BASE-PAIR REGION AROUND THE TERMINUS OF ESCHERICHIA-COLI-K12 DNA-REPLICATION

The physical map of the region on both sides of the terminus of E. coli K12 DNA replication (Bouche, 1982) was related to the genetic markers att.vphi.80, trpABCDE, fnr, rac, trg and man. There are 46 kb (kilobases)/min between trp and man, indicating that conjugative transfer is not slowed down in the region of the terminus. Using this relationship, trq was mapped to 31.4 min and rac was found to extend from 29.6 to 30.1 min. The 3rd phage .lambda.-homologous genetic element of E. coli K12 (Kaiser, 1980), to be called kim, was identified on the map at 34.2 to 34.6 min. The specific activities of fragments labeled at the end of a synchronized replication cycle were measured. They indicate that, for the trp::phage Mu strain studied, the ultimately labeled DNA is at 31.2 .+-. 0.2 min. DNA replication may be delayed or slowed down in a region extending 50 kb on either side of this position.