Studies on head-tail union in bacteriophage lambda

Abstract The kinetics of the joining of tails to heads of phage λ have been studied in vitro . The tails and the heads were obtained by temperature induction of the restrictive host lysogenic for sus A CIt1 and sus L CIt1, respectively. The results show that the reaction can, most simply, be described as due to the kinetic encounter of the two particles. An approximate calculation shows that only about one in a hundred of these collisions is effective in producing an active phage. A few other properties of the tails are described: they adsorb to bacteria as do whole phage. Once adsorbed they can still attach heads and allow, then, injection of the head-contained DNA into the bacteria, which thus become infective centers.