TABLE 1.
Cluster I genes showing high induction (n-fold) in response to strontium stress
| Gene | Gene product | Mean ratio (SrCl2/control) ata:
|
|||
|---|---|---|---|---|---|
| 5 min | 30 min | 60 min | 90 min | ||
| SO1482 | TonB-dependent receptor, putative | 0.6 | 12.8 | 50.4 | 52.2 |
| SO3030 | Siderophore biosynthesis protein (AlcA) | 1.3 | 17.0 | 32.8 | 47.0 |
| SO3031 | Siderophore biosynthesis protein, putative | 1.0 | 20.2 | 132.6 | 498.1 |
| SO3032 | Siderophore biosynthesis protein, putative | 0.7 | 14.5 | 202.4 | 139.4 |
| SO3033 | Ferric alcaligin siderophore receptor | 0.6 | 8.0 | 81.1 | 110.2 |
| SO3344 | Hypothetical protein | 7.5 | 67.4 | 68.7 | 127.9 |
| SO3667 | Conserved hypothetical protein | 0.8 | 17.7 | 121.6 | 130.9 |
| SO3668 | Conserved hypothetical protein | 0.8 | 11.5 | 58.2 | 77.5 |
| SO3669 | Heme transport protein (HugA) | 1.3 | 37.8 | 174.0 | 199.5 |
| SO3670 | TonB1 protein (TonB1) | 6.2 | 79.7 | 155.2 | 225.3 |
| SO3671 | TonB system transport protein ExbB1 (ExbB1) | 3.3 | 180.7 | 379.0 | 567.6 |
| SO3672 | TonB system transport protein ExbD1 (ExbD1) | 2.4 | 55.1 | 108.8 | 175.5 |
| SO3673 | Hemin ABC transporter, periplasmic hemin-binding protein (HmuT) | 1.5 | 34.6 | 104.4 | 83.2 |
| SO3674 | Hemin ABC transporter, permease protein (HmuU) | 1.5 | 24.3 | 60.2 | 70.4 |
| SO3675 | Hemin ABC transporter, ATP-binding protein (HmuV) | 1.2 | 39.9 | 104.1 | 111.3 |
| SO3914 | TonB-dependent receptor, putative | 0.4 | 10.4 | 47.6 | 38.1 |
| SO4636 | Lipoprotein, putative | 13.7 | 53.3 | 75.5 | 62.3 |
a
Relative gene expression is presented as the mean ratio of the fluorescence intensity of SrCl2-exposed cells to that of control cells. Each gene showed significant differential expression (P < 0.05) at a minimum of one time point. The time in minutes is that at which cells were harvested for RNA isolation following addition of 180 mM SrCl2 to the experimental culture.