Second Locus of Bacteriophage P22 Necessary for the Maintenance of Lysogeny

A temperature-sensitive allele of a locus of phage P22, known to be involved in establishment of lysogeny, has been isolated. This mutant, P22 ts mnt, forms stable lysogens at 30 C which are induced by heating to 43 C. This shows that this locus is involved in the maintenance of lysogeny. The ts mnt locus is about 18 recombination units away from the c region. The wild allele, mnt⁺, is dominant over mnt and is responsible for a cytoplasmically diffusible product.