TABLE 6.
Expression of msuD::xylE and atsA in cysI and cysN genetic backgroundsa
| Sulfur sourceb | Strain SLF3
|
Strain SLF4 (cysI)
|
Strain SLF5 (cysN)
|
|||
|---|---|---|---|---|---|---|
| C23O (%) | AtsA (%) | C23O (%) | AtsA (%) | C23O (%) | AtsA (%) | |
| Pn/Met | 100 ± 5 | 100 ± 6 | 100 ± 7 | 100 ± 2 | 100 ± 8 | 100 ± 1 |
| Pn/Met + sulfate | 1.3 ± 0.1 | 11 ± 2 | 1.5 ± 1 | 9.2 ± 2 | 1.8 ± 0.4 | 99 ± 1 |
| Pn/Met + sulfite | 3.3 ± 1 | 9 ± 0.7 | 2.0 ± 0.6 | 5.9 ± 0.2 | 5.5 ± 2 | 4.7 ± 0.1 |
| Pn/Met + sulfide | 2.0 ± 2 | 10 ± 0.7 | 4.5 ± 0.4 | 3.3 ± 1 | 7.9 ± 2 | 1.5 ± 0.3 |
Cells were harvested in mid-exponential phase, and catechol oxygenase (C23O) and arylsulfatase (AtsA) activities in cell extracts were measured as described in Materials and Methods. The results were normalized to 100% for the value obtained after growth with pentanesulfonate or methionine (Pn/Met) (Table 5) and are means and standard deviations from four separate experiments.
Strains SLF3 and SLF5 were grown with pentanesulfonate as a sulfur source (100 μM), and strain SLF4 was grown with methionine (100 μM). (SLF4 is unable to utilize the sulfite derived from pentanesulfonate, whereas SLF5 cannot grow with methionine [17].) Sulfate, sulfite, or sulfide (500 μM) was added as appropriate.