Differential Expression of Bacteriophage Genomes in Vegetative and Sporulating Cells of Bacillus subtilis

Abstract

Two antigenically distinct bacteriophages, (3 and (22, have been isolated and characterized with Bacillus subtilis strain W23 as a host. They differ in plaque morphology, single-step growth characteristics, host range, and thermal stability. The deoxyribonucleic acids isolated from (3 and (22 differ in base composition, density in CsCl and Cs2SO4, sedimentation coefficient, molecular weight, and thermal denaturation temperature. These phages have been used to analyze the ability of B. subtilis to sporulate despite infection by virulent phages. When development of phages (3 and (322 in sporulating cultures was compared with that in log cultures, an increase in the latent periods of infection and a decrease in the burst sizes for the two phages were observed. Sporulating cultures infected with (3 yielded the usual percentage (85%) of mature spores; 80%o of these contained phage determinants and 20% were uninfected. However, cultures infected with (22 lysed. Of the small fraction (0.01 %) which sporulated, 83% were uninfected and 17%o were infected. Phage (3-infected and uninfected spores were examined to distinguish any chemical or physical differences. Preparations of both types of spore contained 81.4 ,ug of dipicolinic acid per mg (dry weight), and examination by phase-contrast microscopy gave no evidence of any difference in outward appearance. A 20%,2G decrease in infected spore count was observed upon heating at 80 C for 10 min. Differences in the infection processes of the two phages prompted an analysis of the transcription process after infection. Deoxyribonucleic acid-ribonucleic acid hybrid analysis of relative amounts of phage-specific and host-specific messenger ribonucleic acid (mRNA) present in infected cells suggested that (33 was unable to repress the synthesis of host mRNA and that (3-specific mRNA synthesis was repressed in sporulation-phase cultures. Phage (322, in contrast, was able to repress host-specific mRNA synthesis in both log-infected and sporulation-infected cells. The results suggest that the differential expression of the phage genomes is due to the relative ability of the phages to repress the host genome.

Recent advances in the social and developmental biology of the myxobacteria.

“…Subsequent germination results in release of the lytic phage (18). A similar phenomenon in phage-infected B. subtilis (265) was subsequently shown to be a result of a change in the template specificity of RNA polymerase during sporulation (139) and, more specifically, a result of the differential effects during development of a cascade of sigma factors (138).…”

The sigma factors of Bacillus subtilis.

“…Virulent bacteriophages, which normally multiply in and lyse vegetatively growing B. subtilis, fail to replicate in bacteria that are sporulating. The phage genome enters the developing cell but becomes trapped and unable to direct the synthesis of progeny phage (276,332). The failure of the viral genomes to be expressed in sporulating B. subtilis parallels a progressive inability of RNAP extracted from these cells to transcribe bacteriophage templates in vitro.…”

Two polypeptides associated with the ribonucleic acid polymerase core of Bacillus subtilis during sporulation

“…Analyses of messenger ribonucleic acid (RNA) present in sporulating cells have indicated the presence of transcripts from genes expressed during both vegetative growth and sporulation and from genes expressed only during sporulation (5,6,24). The reduced ability of sporulating cells to replicate certain phage also suggests that the RNA polymerase (RPase) in sporulating cells may have altered specificity in recognizing or transcribing phage genes (10,19,25). In addition, the isolation of conditional RPase mutants that are temperature sensitive only during sporulation (12; C. Sumida, L. Santo, and R. H. Doi, Abstr.…”