Detection of proteins synthesized during the establishment of lysogeny with phage P22.

A method is described which utilizes pulse labeling with Sa5, starch gel electrophoresis, and autoradiography to detect the synthesis of proteins at various times after infection of Salmonella typhimurium with phage P22. The system was developed especially to study proteins involved in lysogeny. A comparison was made of various infections. These involve the wild-type phage (c+) under conditions producing a high frequency of lysogeny; clear mutants, cl and ~2, each producing lOOy, lysis; and infection with temperature-sensitive mutants unable to make viable phage at 37”. The c+, cl, and cq phage infections caused the appearance of four new protein bands at about the 4th minute after infection. The synthesis of these bands persisted throughout the latent period in the infections leading to phage production and lysis (with phages cl and ~2). In the c+ infection, synthesis continued through the 8th minute, following which the rate decreased until approximately the 20th minute, when synthesis of the bands was no longer detectable. III infection with a particular temperature-sensitive phage mutant, three of the four bands were missing but a new band was observed. The evidence suggests that the proteins whose synthesis was observed are associated with phage production and are phage-specified proteins. The implications of these findings with respect to control phenomena in lysogeny are discussed.