Fig. 1: Fused CapRel homologues are toxin–antitoxin systems that can provide E. coli with robust defence against phages.
From: Direct activation of a bacterial innate immune system by a viral capsid protein
a, Domain organization of long RelA-SpoT homologues (RSH), SAS, toxSAS and the fused subclass of toxSAS toxin–antitoxin systems including CapRelSJ46. b, Cell viability assessed by serial dilutions for strains expressing the N-terminal toxin domain of CapRelSJ46 alone or with the C-terminal antitoxin domain. Ara, arabinose; glu, glucose; Para, arabinose-inducible, glucose-repressible promoter; Plac, IPTG-inducible promoter. c, EOP data for the indicated phages when infecting cells producing CapRelSJ46, CapRelEbc or CapRelKp. d, Serial, tenfold dilutions of the indicated phages spotted on lawns of cells harbouring plasmid expressing CapRelSJ46 or an empty vector (EV). Relative phage concentration is indicated by the height of the wedge. e,f, One-step growth curves measuring plaque-forming units (PFU) during the first round of infection by T4 (e) or SECΦ27 (f) in cells harbouring plasmid expressing CapRelSJ46 or an empty vector. g, Serial dilutions of T7 phage spotted on lawns of cells harbouring plasmids expressing CapRelEbc, CapRelEbc(Y153A) or an empty vector. h, Growth of cells producing CapRelSJ46 or CapRelSJ46(Y155A) or harbouring an empty vector, following infection with T4 at a MOI of 10 or 0.001. Data are mean ± s.d. of eight plate replicates and representative of three independent experiments.
