ANALYSIS OF THE TRO PHENOTYPE OF BACTERIOPHAGE-LAMBDA

Phage λ which possess a mutation in gene cro and a thermolabile repressor are unable to propagate at 42°. This inability, which we have called the Tro effect, is correlated with shut-off of host macromolecular synthesis and the ability to inhibit heteroimmune phage growth in trans. We show that the Tro effect is made up of two trans-acting components and a cis-acting component. The trans-acting components are responsible for inhibition of host macromolecular synthesis and inhibition of heteroimmune phage growth. These effects are most probably due to the overproduction of the Ea10 and N gene products under cro- conditions. The cis-acting component prevents the iλcro- phage from growing without interfering with host macromolecular synthesis or heteroimmune phage growth. The nature of this component remains unknown. © 1979.