FIGURE 1: MafB toxins are involved in growth inhibition of competitor cells.

(A) Genomic organization of mafB and mafI genes. A maf locus contains at least one mafB gene encoding a toxin and one mafI gene encoding the cognate immunity.

(B) Competition between an inhibitor cell expressing a MafB toxin and a target cell that either lacks or expresses the cognate immunity protein. MafI immunity proteins (blue squares) encoded by mafI gene found immediately downstream of mafB gene neutralize cognate toxins (red three-quarter circles) whereas other MafI immunity proteins (green oval) do not confer protection.