Speakers
Description
SPβ-like phages possess a unique lysogeny control system [1]. Our recent work identified the master repressor of SPβ and an essential activator of the lytic cycle [2]; however, the regulatory network governing the lysis-lysogeny decision requires further elucidation [1]. Furthermore, fundamental mechanisms such as virion assembly or the adsorption of SPβ to its bacterial hosts remain poorly understood [3].
We are using time-resolved quantitative proteomics to gain a better understanding of the regulatory dynamics of SPβ. This involves studying (1) MrpR-dependent induction and (2) infection. Analyses of a non-inducible lysogen and an inducible lysogen revealed different dynamics of phage protein accumulation following induction. Time-resolved proteomics suggests that the absence of yosL affects the temporal organization and/or progression of the lytic phage program. Moreover, the study is investigating which temporal changes in the bacterial proteome are associated with successful lytic induction. During phage infection a rapid and sequential accumulation of phage proteins occurs. Most phage proteins were first detected during the early phase of infection, whilst other proteins accumulated at a later stage. This suggests a staggered expression program during infection.
In addition, we investigated the mechanisms underlying phage–host recognition. Isolation and whole-genome sequencing of B. subtilis strains resistant to SPβ infection confirmed the involvement of the minor teichoic acid biosynthesis genes ggaA and ggaB in phage resistance [4]. To identify a potential secondary receptor involved in SPβ adsorption or entry, transposon mutagenesis is currently being employed.
Reference #2
[2] Kohm K, Jalomo-Kharyova E, Krüger A, Basu S, Steinchen W, Bange G, Frunzke J, Hertel R, Commichau FM, Czech L (2023b) Structural and functional characterization of MrpR, the master repressor of the Bacillus subtilis prophage SPβ. Nucleic Acids Res. 51: 9452-9474.
Reference #1
[1] Kohm K, v. Clanner A, Hertel R, Commichau FM (2025) Closely related and yet special - how SPβ phages control lysis-lysogeny decisions. Trends Microbiol. 33: 387-396.
Reference #3
[3] Kohm K Hertel R (2021) The life cycle of SPβ and related phages. Arch Virol 166: 2119-2130.
[4] Estrela AI, De Lencastre H, Archer LJ (1986) Resistance of a Bacillus subtilis mutant to a group of temperate bacteriophages. Microbiology 132:411–415.
