The effect of deleting ytpB on bacitracin sensitivity is dependent upon BceAB and BcrC in both trpC2 and trp+ backgrounds. (A) Bacitracin disk diffusion assays for WT (168 trpC2) and isogenic strains: ΔytpB (HB13350), ΔbcrC (HB13348), ΔbcrC ΔytpB (HB13351), ΔbceAB (HB0928), ΔbceAB ΔytpB (HB13354), ΔbceAB ΔbcrC (HB13355), and ΔbceAB ΔbcrC ΔytpB (HB13356); (B) Bacitracin disk diffusion assays (using zinc bacitracin) in trp+ background for WT (HB13387) and isogenic strains: ΔytpB (HB13389), ΔbcrC (HB17031), ΔbcrC ΔytpB (HB17033), ΔbceAB (HB13388), ΔbceAB ΔytpB (HB13390), ΔbceAB ΔbcrC (HB17032), and ΔbceAB ΔbcrC ΔytpB (HB17034).