[Mapping of the c-region of phage phi80]

A set of c-mutants of the phage phi80 is isolated. These mutants fit into three genes. According to plaque morphology and frequency of lysogenization of mutants, the genes were named cI, cII and cIII as it was previously done for phage lambda. Their order, determinated by mutant phage crosses, is cIII-sus326-cI-cII-sus250. Sus326 is a mutation in the gene 15, so it is probably an analogue of the N gene of the phage lambda. Thermoinducible mutants of the phage phi80 cts11 and cts12 correspond to the mutant types cItsB and cItsA of the phage lambda and they complement each other. Thus, it is supposed that phi80 phage repressor molecules consist of few protein subunits.