Genetic map of coliphage 186 from a novel use of marker rescue frequencies.

A genetic map of phage 186 has been constructed, using the frequency of marker rescue from 186 mutant prophages for genes to the left of att, and int promoted recombination for genes to its right. At the left end of the genome lie 7 genes involved in the formation of the phage head, followed to the right by the lysis gene P, a gene (O) of unknown function, and a group of 11 genes involved in the formation of the phage tail. Gene B, the late control gene, lies to the right of this group but to the left of the phage attachment site. To the right of the att site lie the non-essential genes (cI and cII) involved in lysogen formation and the gene (A) required for 186 DNA synthesis.