title: Viral evasion of a bacterial suicide system by RNA-based molecular mimicry enables infectious altruism.
abstract: Abortive infection, during which an infected bacterial cell commits altruistic suicide to destroy the replicating bacteriophage and protect the clonal population, can be mediated by toxin-antitoxin systems such as the Type III protein-RNA toxin-antitoxin system, ToxIN. A flagellum-dependent bacteriophage of the Myoviridae, ΦTE, evolved rare mutants that "escaped" ToxIN-mediated abortive infection within Pectobacterium atrosepticum. Wild-type ΦTE encoded a short sequence similar to the repetitive nucleotide sequence of the RNA antitoxin, ToxI, from ToxIN. The ΦTE escape mutants had expanded the number of these "pseudo-ToxI" genetic repeats and, in one case, an escape phage had "hijacked" ToxI from the plasmid-borne toxIN locus, through recombination. Expression of the pseudo-ToxI repeats during ΦTE infection allowed the phage to replicate, unaffected by ToxIN, through RNA-based molecular mimicry. This is the first example of a non-coding RNA encoded by a phage that evolves by selective expansion and recombination to enable viral suppression of a defensive bacterial suicide system. Furthermore, the ΦTE escape phages had evolved enhanced capacity to transduce replicons expressing ToxIN, demonstrating virus-mediated horizontal transfer of genetic altruism.
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Tim R
authors.initials: TR
authors.lastname: Blower
authors.forename: Terry J
authors.initials: TJ
authors.lastname: Evans
authors.forename: Rita
authors.initials: R
authors.lastname: Przybilski
authors.forename: Peter C
authors.initials: PC
authors.lastname: Fineran
authors.forename: George P C
authors.initials: GP
authors.lastname: Salmond
mesh_terms: D001435:Bacteriophages / Q000235:genetics* / Q000648:ultrastructure; D001483:Base Sequence; D005075:Biological Evolution; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D015870:Gene Expression; D023061:Gene Order; D016679:Genome, Viral; D062105:Molecular Docking Simulation; D018716:Molecular Mimicry; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D044043:Pectobacterium / Q000235:genetics* / Q000821:virology*; D011487:Protein Conformation; D040641:Quantitative Trait Loci; D012329:RNA, Bacterial / Q000235:genetics*; D016415:Sequence Alignment; D014118:Toxins, Biological / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014161:Transduction, Genetic
chemical_list: D004279:DNA, Viral; D012329:RNA, Bacterial; D014118:Toxins, Biological