TABLE 2

Biological activity of McB mutants with substitutions at position 69a

MicrocinMinimal concn (μM) producing growth inhibition zone
BL21(DE3)BL21(DE3) overexpressed SbmA
McBwt0.060.006
McB1–6830.06
McB I69L0.060.006
McB I69T0.60.06
McB I69K60.12
McB I69E300.6
Cfx0.30.3
McC1010
Amp200200
  • a The indicated McB mutants and wild-type McB were purified (most material was in the type XΔ0 form) and used to determine the ability to inhibit the growth of E. coli BL21(DE3) cells with or without an sbmA expression plasmid under conditions of induction of the plasmid-borne gene as described in Materials and Methods. Ciprofloxacin (Cfx), microcin C (McC), and ampicillin (Amp) were used as controls.