A colicin-tolerant mutant of Escherichia coli with reduced levels of cyclic AMP and the regulation of lambdoid phage lysogeny

Wild-type phages lambda and phi80 plate very differently on the colicin-tolerant mutant 483 (originally designated as ER437 by Nomura and Witten 1967) at different incubation temperatures. Phage lambda gives very high levels of lysogenic colonies at all temperatures and thus reduced plating effieiencies. In marked contrast, phage phi80 plates with normal efficiencies at all growth temperatures, forming turbid-solid centred plaques at 30° and clear plaques at elevated growth temperatures. The addition of cyclic AMP to the assay plates did not reverse the plating characteristics for either phage. A more detailed investigation of phage phi80 plating showed that the formation of clear plaques at 40°C resulted from a failure to establish lysogeny rather than from a lack of maintenance of an already established lysogenic condition. Moreover, studies of phage growth in strain 483 at different growth temperatures show that cyclic AMP improves the capacity of the mutant to grow phage phi80vir. The possible relationship of this phage growth and changes observed in the proteins of the cell envelope components were examined by studying a large group of phenotypic revertants of strain 483. The multiple effects observed can be explained if the RNA polymerase complex of mutant 483 gives rise to differences in the recognition of some promoters. This leads to a change in the proportions of some membrane proteins of the cell which, in turn, give rise to the altered developmental patterns of both phages lambda and phi80