Transposition mutagenesis of bacteriophage lambda. A new gene affecting cell lysis

Insertions of Tn903, a transposable kanamycin-resistance element, in bacteriophage lambda at 0.95 on the lambda physical map adversely affect growth of the phage. These insertion mutants are able to assemble particles, but are unable to lyse the infected cell properly. The mutants define a new genetic complementation group that we have designated as gene Rz. Cells infected with the λRz:: Tn903 isolates will, at the normal time of lysis, change their shape from a rod to a sphere. These spheres are stable in dilute buffers with Mg²⁺ but are lysed with EDTA. In addition, these results demonstrate the utility of transposition mutagenesis in refining the genetic map of even so intensely studied a genome as lambda.