Table 1.
PAPS reductase activity, APS reductase activity, and growth phenotype of cysH mutant, functionallycomplemented and wild-type E. coli strains, and activity of the recombinant PRH19 protein
| E. coli strain | Ability to grow on sulfate as sole sulfur source | PAPS reductase activity,
pmol·min−1·mg·protein−1
|
APS
reductase activity,
pmol·min−1·mg·protein−1
|
||
|---|---|---|---|---|---|
| + trx | − trx | + trx | − trx | ||
| TB1 (wild type) | ND | 482.7 | 26.8 | 0.9 | 1.0 |
| JM96 (cysH mutant) | − | 0.0 | 0.0 | 0.5 | 0.4 |
| JM96/pYES | − | 0.2 | 0.0 | 0.5 | 0.5 |
| JM96/pPRH19 | + | 1.3 | 1.9 | 601.7 | 588.0 |
| JM96/pPRH26 | + | 0.8 | 0.9 | 140.0 | 211.7 |
| JM96/pPRH43 | + | 1.1 | 1.4 | 732.5 | 766.5 |
| 6×His PRH19 | 36.7 | 50.3 | 12,363.0 | 13,335.0 | |
Cell-free extracts from the cysH mutant JM96; JM96 retransformed with either pYES, pPRH19, PRH26, or pPRH43; wild-type strain TB1, and recombinant 6×His PRH19 protein (1 μg) were assayed for PAPS reductase activity and APS reductase activity in the presence or absence of recombinant E. coli thioredoxin (trx) (4.5 μg). Ability (+) or inability (−) of the strain to grow on M9 minimal medium with sulfate as sole sulfur source was also scored. ND, not determined.