Initiation by bacteriophage T1 of DNA packaging at a site between the P and Q genes of bacteriophage lambda

The growth of phage T1 on cells tandemly lysogenic for heteroimmune lambdoid prophages leads to a nonrandom packaging of lambda DNA by T1. A site, called esp-lambda, is located between the P and Q genes of lambda and results in increased packaging to the left by T1. When cloned into pBR322, the esp-lambda site causes a significant increase in transduction of the plasmid by T1. The nin5 deletion inactivates esp-lambda.