Delayed lysis with salmonella bacteriophage p22: induction of lysis by addition of cysteine or histidine to the growth medium.
A mutant (Lys(-)) of Salmonella bacteriophage P22 showed a delay in lysis of more than 3 hr in infections in unsupplemented M9 medium. The infected cells were induced to lyse during that interval by addition of histidine or sulfhydryl compounds cysteine, mercaptoethanol, glutathione, or ergothioneine. Urocanic acid, the first intermediate in the catabolic histidine pathway, did not induce lysis, nor did histamine, imidazolelactate, or carnosine. None of the other amino acids common to protein had any inductive effect. Both the d and l forms of histidine were effective in inducing lysis, suggesting that the incorporation of the histidine into protein is not involved. Chloramphenicol inhibited lysis when added at 60 min with or without histidine, but did not inhibit the induction of lysis when added with cysteine. Bacterial cells infected with Lys(+) phage were induced to lyse prematurely when cysteine was added at 30 min but not at 20 min of infection. Iodoacetate inhibited lysis of Lys(+)-infected cells when added at 20 min but not at 30 min.
Cohen
L W
LW
Seaver Laboratory of Biology, Pomona College, Claremont, California 91711.