TABLE 3.
β-Lactamase specific activities and Qscs of novobiocin-treated strain WT, reference strain JTT1, and its topoisomerase mutants
| Strain | Reference | Δsc (%)a | Novobiocin concn (μg/ml)b | β-Lactamase sp act (U/mg)c for strain carrying plasmid:
|
Qsc | ΔQsc (%)d | ||
|---|---|---|---|---|---|---|---|---|
| pBR328 | pBP523 | pBP524 | ||||||
| WT | 23 | 10.8 | 7.5 | 12.1 | 1.61 | 0 | ||
| WT | 25 | 15.1 | 13.6 | 13.8 | 1.01 | −37 | ||
| WT | 50 | 21.3 | 26.1 | 19.6 | 0.75 | −53 | ||
| WT | 75 | 24.6 | 29.4 | 13.2 | 0.45 | −72 | ||
| JTT1 | 58 | 0 | NDe | 4.1 | 7.7 | 1.87 | 0 | |
| KD112 | 57 | −17 | ND | 5.8 | 8.3 | 1.44 | −23 | |
| RS 2 | 58 | +8 | ND | 1.2 | 6.8 | 5.54 | +296 | |
a
The differences in the degree of supercoiling (Δ sc) relative to that of the wild-type parent (JTT1; Δsc = 0) are from reference 58. A negative value indicates a reduction in the degree of negative supercoiling, and a positive value indicates an increase.
b
Cells were grown in the presence of subinhibitory concentrations of novobiocin as indicated.
c
The bla gene was transcriptionally fused to promoter pbla (plasmid pBR328), pgyrA (plasmid pBP523), or ptopA (plasmid pBP524).
d
Differences in Qsc values (ΔQsc) were calculated in comparison to the respective isogenic parent (ΔQsc = 0).
e
ND, not determined.