Effect of antibiotics on certain aspects of bacteriophage SP-15 development in Bacillus subtilis W23

Abstract

Bacillus subtilis W23 was infected with bacteriophage SP-15. Two waves of phage-specific RNA synthesis were observed. Wave I was prereplicative, and wave II was coincident with replication of the viral genome. To determine the temporal appearance of general classes of phage-coded messengers and proteins, we studied the dependence of lysozyme synthesis, phage production, and DNA synthesis on time of addition of transcriptional and translational inhibitors. Lysozyme synthesis started to become refractile to a variety of transcriptional inhibitors (rifampin, streptolydigin, and actinomycin D) between 20 and 22 min postinfection and was completely refractile by 30 min. Nevertheless, functional

Production and expression of dTMP-enriched DNA of bacteriophage SP15

“…9A). Therefore, potentially translatable messengers for lytic enzymes were present well in advance of their protein products (9). In FUdR-inhibited cultures, mRNA's appeared at 45 min, followed by the proteins at about 70 min (Fig.…”

“…Accordingly, we studied the syntheses of lytic proteins and structural proteins under FUdR-inhibited and rescued conditions. These are the only known SP15 proteins whose syntheses occur after the onset of viral replication (9).…”

“…Delayed appearance of certain proteins under FUdR-inhibited conditions could reflect delayed transcription or translation or both. To obtain additional information on this point, experiments were done that measured the dependence of protein synthesis on the time of addition of antibiotic inhibitors of transcription (9,21). The antibiotics used were rifampin and streptolydigin, selective inhibitors of RNA chain initiation and elongation, respectively (7,29,37).…”

“…harvested by centrifugation at 9,000 x g for 1 min and suspended in 0.9 volume of fresh, warm medium that contained 200 uM 6-(p-hydroxyphenylazo)-uracil, a selective inhibitor of bacterial DNA synthesis (5,9,25). In experiments involving FUdR and dThd, the new medium also contained 1 mg of uridine per ml to prevent any incorporation of 5-fluorouracil into RNA (10) and to suppress dThd phosphorylase activity (3,6,34), thereby augmenting salvage of both deoxynucleosides.…”

“…Antiserum specific for SP15 (serum value, 12,000) was prepared by J. Konvicka and supplied by M. Mandel. The lytic enzyme assay is detailed elsewhere (9). Incorporation of labeled precursors into DNA was determined by the method of Lembach and Buchanan (16).…”