Evolution of Pectobacterium bacteriophage ΦM1 to escape two bifunctional Type III toxin-antitoxin and abortive infection systems through mutations in a single viral gene

Blower, T.R.; Chai, R.; Przybilski, R.; Chindhy, S.; Fang, X.; Kidman, S.E.; Tan, H.; Luisi, B.F.; Fineran, P.C.; Salmond, G.P.C.

Abstract

Some bacteria, when infected by their viral parasites (bacteriophages), undergo a suicidal response that also terminates productive viral replication (abortive infection; Abi). This response can be viewed as an altruistic act protecting the uninfected bacterial clonal population. Abortive infection can occur through the action of Type III protein-RNA toxin-antitoxin (TA) systems, such as ToxINPa from the phytopathogen, Pectobacterium atrosepticum. Rare spontaneous mutants evolved in the generalized transducing phage, ΦM1, which escaped ToxINPa-mediated abortive infection in P. atrosepticum. ΦM1 is a member of the Podoviridae and member of the “KMV-like viruses”, a subset of the T7 supergroup. Genomic sequencing of ΦM1 escape mutants revealed single-base changes which clustered in a single open reading frame. The “escape” gene product, M1-23, was highly toxic to the host bacterium when over-expressed, but mutations in M1-23 that enabled an escape phenotype caused M1-23 to be less toxic. M1-23 is encoded within the DNA metabolism modular section of the phage genome, and when it was over-expressed, it co-purified with the host nucleotide excision repair protein, UvrA. While the M1-23 protein interacted with UvrA in co-immunoprecipitation assays, a UvrA mutant strain still aborted ΦM1, suggesting that the interaction is not critical for the Type III TA Abi activity. Additionally, ΦM1 escaped a heterologous Type III TA system (TenpINPl) from Photorhabdus luminescens (reconstituted in P. atrosepticum) through mutations in the same protein, M1-23. The mechanistic action of M1-23 is currently unknown but further analysis of this protein could provide insights into the mode of activation of both systems.

Citation

Blower, T., Chai, R., Przybilski, R., Chindhy, S., Fang, X., Kidman, S., …Salmond, G. (2017). Evolution of Pectobacterium bacteriophage ΦM1 to escape two bifunctional Type III toxin-antitoxin and abortive infection systems through mutations in a single viral gene. Applied and Environmental Microbiology, 83(8), e03229-16. https://doi.org/10.1128/aem.03229-16

• Journal Article Type: Article
• Acceptance Date: Jan 26, 2017
• Online Publication Date: Feb 3, 2017
• Publication Date: Apr 1, 2017
• Deposit Date: Feb 9, 2017
• Publicly Available Date: Feb 9, 2017
• Journal: Applied and Environmental Microbiology
• Print ISSN: 0099-2240
• Electronic ISSN: 1098-5336
• Publisher: American Society for Microbiology
• Peer Reviewed: Peer Reviewed
• Volume: 83
• Issue: 8
• Article Number: e03229-16
• Pages: e03229-16
• DOI: https://doi.org/10.1128/aem.03229-16
• Public URL: https://durham-repository.worktribe.com/output/1365685