TABLE 3.
β-Galactosidase activities of Y. pestis KIM6+ derivatives containing p1::lacZ or p2::lacZ reporter plasmid
| Strain | β-Galactosidase activity of cells grown in deferrated PMH witha:
|
β-Galactosidase ratiosa
|
|||||
|---|---|---|---|---|---|---|---|
| No added iron | 10 μM FeCl3 | 10 μM Heminb | 2.5 μM Hemoglobinb | −Fe/+Fe | −Fe/+Hemin | −Fe/ +Hemoglobin | |
| With pHMU44 (p1::lacZ) | |||||||
| KIM6+ | 26,946 (±4,802) | 1,458 (±551) | 23,606 (±3,430) | 12,312 (±1,528) | 20.9 (±9.2) | 1.1 (±0.1) | 2.2 (±0.4) |
| KIM6-2044.1+ (ΔhmuP′RSTUV-2044.1) | 27,544 (±3,679) | 962 (±150) | 24,798 (±3,386) | 19,764 (±4,009) | 29.1 (±4.9) | 1.2 (±0.1) | 1.6 (±0.2) |
| KIM6-2030+ (fur::kan-9) | 27,960 (±3,444) | 26,300 (±3,653) | NTc | NT | 1.0 (±0.2) | NT | NT |
| With pHMU55 (p2::lacZ) | |||||||
| KIM6+ | 1,604 (±113) | 1,222 (±188) | 1,484 (±81) | 955 (±131) | 1.3 (±0.3) | 1.1 (±0.1) | 1.7 (±0.4) |
| KIM6-2044.1+ (ΔhmuP′RSTUV-2044.1) | 911 (±155) | 567 (±49) | 1,211 (±76) | 596 (±43) | 1.6 (±0.2) | 0.7 (±0.1) | 1.5 (±0.2) |
| KIM6-2030+ (fur::kan-9) | 1,098 (±161) | 828 (±73) | NT | NT | 1.3 (±0.3) | NT | NT |
a
Cells were grown approximately six generations in deferrated PMH at 37°C and harvested during mid-log-phase growth. β-Galactosidase activity is expressed in Miller units (35), and the values represent an average of individual reactions from whole-cell lysates. Mean β-galactosidase ratios were obtained from averaged β-galactosidase activities from three or four experiments. Standard deviations are shown in parentheses.
b
Desferrioxamine mesylate (Desferal) was added to a final concentration of 20 μM to chelate any contaminating inorganic iron in the hemin and hemoglobin solutions.
c
NT, not tested.