Polyamine Synthesis and Accumulation in Escherichia coli Infected with Bacteriophage R17

Abstract

We have studied the biosynthesis of polyamines during the multiplication of the RNA bacteriophage R17. R17-sensitive strains of Escherichia coli were derived from the stringent CP78 and the relaxed mutant derivative CP79. The cells were infected with R17 in the presence or absence of arginine, a required amino acid, and both the RNA and polyamine contents of the bacteria were determined before and after the infection. The uninfected CP79 rel derivative accumulated RNA and spermidine in the absence of arginine, unlike the stringent organism that accumulated neither under these conditions. After R17 infection, the stringent strain accumulated RNA and spermidine in the presence or absence of arginine. The data indicate a close correlation between the synthesis of RNA and spermidine, suggesting a significant role for this polyamine in the multiplication of phage R17.

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

“…Consequently, the ratio ([rate without arginine]-[rate with arginine]) increased during infection. These observations are in good agreement with the data reported previously (6). Since the ratio in the stringent cultures increased from 3.4 to 43% (or 12.6-fold) at 25 min after infection, it appears that the infection caused a relaxation of the stringent mechanism.…”

“…Bacteria and bacteriophage. Isolation of phage R17-sensitive derivatives of E. coli strains CP78 and CP79 and the conditions for growth have been described previously (6). The conditions for the infection by bacteriophage R17 also followed the procedures described (6).…”

“…Analysis of nucleotide pools. To determine specific radioactivity of UTP and CTP in cells, a portion (125 ml) of the radioactive culture (labeled with ["4C]uracil, 6.67 nCi/0.62 Ag per ml) was centrifuged and washed at room temperature and extracted with 60% methanol according to the procedure described by Munch-Petersen et al (7). The extraction was carried out by suspending the washed cells in 2 ml of 60% methanol at -20 C. The mixture was stored at -20 C overnight.…”

“…In a previous paper (6) we have shown that infection of E. coli CP78 by bacteriophage R17 resulted in a significant accumulation of both RNA and spermidine. Although CP78 is a rigorously stringent strain, i.e., it does not accumulate either RNA or spermidine in the absence of arginine, a required amino acid, infection in the absence of arginine nevertheless produced a marked synthesis of both RNA and spermidine.…”

Diverse Functions of Polyamines in Virus Infection

“…Bacteriophages also manipulate bacterial polyamine levels, presumably to enhance phage functions. For instance, bacteriophage R17 promotes spermidine accumulation in the infected E. coli cell [17,18]. However, this phenotype is not shared with all bacteriophages.…”