Bactericidal activity of extracellular full-length MccE492 and of C-terminally truncated MceA. (A) Growth inhibition assay of a lawn of MccE492-sensitive cells [BL21(pBR322, pBAD101)] overlaid with 5 μl of overnight culture of AB7 with pBAD101 (vector), pAB10 (ABC-MceA), or pAB10-1C (ABC-MceA-1C) on an LB plate supplemented with 0.2% arabinose. Strain AB7 contains all the genes of the MccE492 system, except mceA, in plasmids pAB4 and pAB7. The plate was incubated overnight at 37°C. Note that both the lawn and the tested cultures are growing on this plate. (B) MceA immunoblot of the media of cultures of AB7 with pBAD101 (vector), pAB10 (ABC-MceA), or pAB10-1C (ABC-MceA-1C). Media were obtained from 24-h cultures in M9 minimal medium supplemented with 0.2% arabinose.