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The Role of Gene S

Sankar Adhya, Arup Sen, Sankar Mitra


At least two λ genes, S and R, are involved in the lysis of the host. The gene R codes for the phage specific lysozyme which disintegrates the cell wall (Campbell and del Campillo-Campbell, 1963). but the role of the gene S is not clearly understood. Harris et al. (1967) showed that an S mutant multiplies in the host after infection, but with no subsequent lysis. This behavior was already known for mutations in gene R. The S mutants are characteristically different from the R mutants in that (a) the final intracellular phage concentration of S mutants is at least ten times higher than that of R mutants or of wild-type λ, and (b) the host cells in which the S mutants are multiplying continue to grow for some time, whereas bacteria with R mutants stop growing at the end of the normal latent period.

The discovery of suppressible nonsense and temperature-sensitive mutations in gene S (Goldberg and Howe. 1969; Harris et al., 1967) suggests that the product of S gene is a protein. In the present investigations, effects of mutations in genes S and R on DNA synthesis and O2 uptake of the host cells have been investigated.

In order to see if growth of S mutants, like R mutants in induced lysogens interrupts DNA synthesis, the rate of DNA synthesis has been measured in a nonlysogen, and in lysogens of S and R mutants after induction (Fig. 1). It is clear that the rate of DNA...

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