Rolling circle replicative structure of bacteriophage lambda DNA in a recombination deficient system.

Rolling-circle replicating structures which represent late stage lambda DNA replication can be detected among intracellular phage lambda DNA molecules under recombination deficient conditions as well as in wild-type infections. Furthermore, if initiation of lambda replication is delayed until the late stage of lambda infection, then nearly all replicating molecules are rolling-circle, even in the first round. Thus neither genetic recombination nor termination of a round of replication are required for generation of rolling-circle replicating molecules of lambda DNA.