TABLE 2.
Meropenem sensitivity and avibactam potentiation of transposon mutantsa
| Gene | Function | Tn-seq class | Insertion site (bp)b | Meropenem MIC (μg/mL) |
ΔMIC | |
|---|---|---|---|---|---|---|
| –avibactam | +avibactam | |||||
| Wild type | – | – | – | 12 ± 0.8 | 0.25 | 48 |
| trpB | Tryptophan synthesis | – | 381 (1,230) | 12 | 0.25 | 48 |
| 670 (1,230) | 11 ± 1 | 0.25 | 44 | |||
| bla OXA-23 | β-Lactamase OXA-23 | 1 | 121 (822) | 3 | 0.09 | 33 |
| 230 (822) | 3 | 0.09 | 33 | |||
| lptE | LOS synthesis | 1 | 18 (510) | 0.67 ± 0.3 | 0.009 | 74 |
| 229 (510) | 0.31 ± 0.12 | 0.008 | 39 | |||
| 384 (510) | 0.25 | 0.008 | 32 | |||
| 404 (510) | 0.38 | 0.008 | 48 | |||
| pbpG | Peptidoglycan metabolism | 1 | 277 (1,008) | 3.5 ± 0.6 | 0.11 ± 0.02 | 32 |
| 140 (1,008) | 4 | 0.09 | 44 | |||
| znuA | Zinc transport | 1 | 391 (840) | 6 | 0.12 | 50 |
| 211 (840) | 6 | 0.12 | 50 | |||
| gna | Capsule synthesis | 1 | 319 (1,275) | 3.5 ± 0.6 | 0.03 | 117 |
| 157 (1,275) | 4 | 0.06 | 67 | |||
| dsbA | Disulfide formation | 1 | 336 (618) | 3.5 ± 0.7 | – | – |
| 184 (618) | 3.8 ± 0.5 | 0.19 | 20 | |||
| 64 (618) | 4 | 0.16 ± 0.04 | 25 | |||
| dsbB | Disulfide formation | 2 | 56 (516) | 6 | 0.25 | 24 |
| 106 (516) | 5 ± 1.4 | 0.25 | 20 | |||
| ampG | Peptidoglycan recycling | 2 | 460 (2,190) | 4 | 0.09 | 44 |
| 779 (2,190) | 4 | 0.09 | 44 | |||
| ABUW_0466 | Unknown | 2 | 320 (663) | 6 | 0.25 | 24 |
| 470 (663) | 6 | 0.25 | 24 | |||
| rpoE | Sigma factor | 2 | 236 (615) | 6 | 0.09 | 67 |
| lpxL | LOS synthesis | 2 | 314 (936) | 3 | 0.05 | 60 |
| lpsB | LOS synthesis | 2 | 333 (1,101) | 4 | 0.05 | 80 |
| 742 (1,101) | 2.5 ± 2.1 | 0.04 ± 0.01 | 63 | |||
| bla GES-14 | β-lactamase GES-14 | 4 | 378 (864) | 11 ± 1.4 | 0.25 | 44 |
| ompA | Outer membrane protein | – | 103 (1,062) | 4 | –c | – |
| 943 (1,062) | 3 | –c | – | |||
| ompR | Two-component regulation | – | 502 (765) | 2.75 ± 0.5 | 0.05 | 55 |
| 411 (765) | 2.5 ± 0.6 | 0.05 | 50 | |||
| envZ | Two-component regulation | 4 | 888 (1,458) | 6 | –c | – |
The average values of two to seven efficiency-of-plating assays for each mutant are presented. Nonzero sample standard deviations are shown. A complete list of mutants identified by Tn-seq is shown in Table S2, including their class assignments based on depletion after growth in the presence of meropenem. Additional genes with verified but smaller individual mutant meropenem sensitivities (minus avibactam) (ΔMIC 6 to 10) were qhbB (capsule synthesis); bfmR, rseP, and dksA (regulation); mrdA, dacC, elsL, and rlpA (peptidoglycan synthesis); ABUW_0460 (unknown function); and znuC (zinc transport). The ompA and ompR genes showed low mutant read recovery in Tn-seq and were not assigned a class.
Transposon insertion position in gene (gene length).
Sensitive to avibactam alone.