Figure 7. The F pilus is required for CdiA-CT⁵³⁶ import.

E. coli X90 and its derivatives were treated with purified CdiA-CT⁵³⁶ where indicated (+CT), and cell growth was monitored by OD₆₀₀ measurements. A) Wild-type X90 is indicated as F′ and cured cells as F⁻. The F′::Tn10 episome and pOX38::gent (pOX38) were introduced into cured X90 and the resulting cells treated with CdiA-CT⁵³⁶. B) E. coli X90 ΔtraA::cat and ΔtraT::cat mutants. C) E. coli X90 ΔtraA::cat cells complemented with plasmid-borne traA. D) and E) E. coli X90 ΔtraA::cat cells complemented with plasmid-borne traA(D74G) and traA(G120C). Error bars correspond to the standard error of the mean for three independent experiments. F) E. coli X90 ΔtrbI::cat mutant. Wild-type (trbI⁺) cells expressing trbI from a plasmid (pTrbI) were also tested for toxin-resistance.