Synthesis of viral and rRNA in bacteriophage R17 infection of a stringent strain of Escherichia coli.

Abstract

A previous paper (1973) indicated that infection with bacteriophage R17 permits the synthesis of RNA and spermidine in Escherichia coli (CP78 in the absence of the exogenous essential amino acid, arginine. We have now isolated RNA formed under such conditions and analyzed the newly synthesized species by agarose-acrylamide electrophoresis. It has been shown that infection of the stringent cells in the absence of exogenous arginine resulted in a marked incorporation of uracil into rRNA, as well as into R17 RNA. It was shown that, although the organism was nonauxotrophic for uracil, addition of [-14C]uracil resulted in the rapid formation of TUP, the specific radioactivity of which approached that of the exogenous uracil. This indicated that the incorporation of exogenous uracil into rRNA in R17 infection of the stringent strain reflected a true stimulated synthesis of this nucleic acid. Infection of the essentially isogenic relaxed strain, CP79, under the same conditions inhibited the RNA synthesis to a much less extent than the inhibition caused during the normal infection. These observations provide another example of the close correlation between synthesis of spermidine and of host RNA, even in cells infected by an RNA bacteriophage.