Table 1.
Minimal Inhibitory Concentration (MIC) values for several structurally unrelated drugs.
| Strain | Flexibility | Minimal Inhibitory Concentration (MIC, μg/mL) | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| CLX | BZK | EtBr | CV | NB | R6G | MINO | ACR | EM | ||
| ΔtolC | 0.25 | 4 | 8 | 2 | 2 | 32 | 0.5 | 8 | 2 | |
| acrB-KO | 2 | 4 | 16 | 2 | 16 | 32 | 0.5 | 16 | 4 | |
| Wild-type AcrB | 256 | 512 | 1,024 | 16 | 1,024 | 8,192 | >2 | 1,024 | 128 | |
| Truncated (6 amino acids) | Lowest | 16 | 32 | 256 | 8 | 128 | 256 | 0.5 | 32 | 32 |
| Truncated (3 amino acids) | 256 | 128 | 1,024 | 16 | 1,024 | 8,192 | >2 | 1,024 | 128 | |
| Pro single (L868P) | 256 | 128 | 1,024 | 16 | 1,024 | 8,192 | >2 | 512 | 128 | |
| Pro single (Q872P) | 256 | 256 | 1,024 | 16 | 1,024 | 8,192 | >2 | 1,024 | 128 | |
| Pro double (L868P+Q872P) | 256 | 512 | 1,024 | 16 | 1,024 | 8,192 | >2 | 1,024 | 128 | |
| Elongated (+GGS) | 512 | 512 | >1,024 | 16 | 1,024 | >8,192 | >2 | 1,024 | 128 | |
| Elongated (+GGSGGS) | 256 | 512 | 1,024 | 16 | 1,024 | 8,192 | >2 | 1,024 | 128 | |
| Elongated (+GGSGGSGGS) | Highest | 512 | 512 | 1,024 | 16 | 1,024 | 8,192 | >2 | 1,024 | 128 |
MIC concentrations were determined by step-wise dilutions gradients of the compounds in agar plates and the growth ability of MG1655ΔacrB E. coli cells (expressing the proteins from the plasmid) was determined. Values are in μg/mL. The colors indicate the degree of flexibility from low (red) to high (blue). Abbreviations: CLX, cloxacillin; BZK, benzalkonium; EtBr, ethidium bromide; CV, crystal violet; NB, novobiocin; R6G, rhodamine 6G; MINO, minocycline; ACR, acriflavine; EM, erythromycin.