The life cycle of SPβ and related phages

Abstract

Phages are viruses of bacteria and are the smallest and most common biological entities in the environment. They can reproduce immediately after infection or integrate as a prophage into their host genome. SPβ is a prophage of the Gram-positive model organism Bacillus subtilis 168, and it has been known for more than 50 years. It is sensitive to dsDNA damage and is induced through exposure to mitomycin C or UV radiation. When induced from the prophage, SPβ requires 90 min to produce and release about 30 virions. Genomes of sequenced related strains range between 128 and 140 kb, and particle-packed dsDNA exhibits terminal redundancy. Formed particles are of the Siphoviridae morphotype. Related isolates are known to infect other B.subtilis clade members. When infecting a new host, SPβ presumably follows a two-step strategy, adsorbing primarily to teichoic acid and secondarily to a yet unknown factor. Once in the host, SPβ-related phages pass through complex lysis–lysogeny decisions and either enter a lytic cycle or integrate as a dormant prophage. As prophages, SPβ-related phages integrate at the host chromosome's replication terminus, and frequently into the spsM or kamA gene. As a prophage, it imparts additional properties to its host via phage-encoded proteins. The most notable of these functional proteins is sublancin 168, which is used as a molecular weapon by the host and ensures prophage maintenance. In this review, we summarise the existing knowledge about the biology of the phage regarding its life cycle and discuss its potential as a research object.

Down in the pond: Isolation and characterization of a new Serratia marcescens strain (LVF3) from the surface water near frog’s lettuce (Groenlandia densa)

“…The second predicted prophage was unable to form particles under the employed experimental conditions. As prophages can mediate resistance against related phages, a low number or absence of prophages in the genome is required for a potential host strain employed for phage isolation [ 23 ] and covering viral diversity in an isolation experiment.…”

“…There they inactivate, and replicate together with their host, resulting in a prophage and a lysogenic bacterium. A prophage can impart new properties to its host through the addition of its genetic material, thereby protecting it from infection with related and unrelated viruses [ 23 ].…”

Dormant phages communicate to control exit from lysogeny

“…The mechanism by which aimX promotes initiation of the lytic cycle and its interaction with the DNA-damage detection network in SPβ-like phages remains unknown, stressing the need to further study the lysogeny system of this poorly characterized family 42 . Nevertheless, we have shown that in these phages, the inputs of DNA damage and arbitrium signaling are integrated downstream of aimX expression.…”

“…The mechanism by which aimX promotes initiation of the lytic cycle and its interaction with the DNA-damage detection network in SPꞵ-like phages remains unknown, stressing the need to further study the lysogeny system of this poorly characterized family 42 .…”

AimR Adopts Preexisting Dimer Conformations for Specific Target Recognition in Lysis-Lysogeny Decisions of Bacillus Phage phi3T

“…phi3T phage is a temperate phage, parasitic in Bacillus subtilis [ 13 ]. Mitomycin C treatment can promote phi3T phage lysis [ 14 ], but it was unknown how the phage itself switches between lytic and lysogenic life cycles.…”