Table 3.
Enzymatic activities encoded by FOL1
| DHNA (nmol/mg h) | HPPK (nmol/mg h) | DHPS (nmol/mg h) | |
|---|---|---|---|
| S. cerevisiae strain | |||
| FOL1 | h6.0 ± 1 | 1.0 ± 0.5 | 16 |
| fol1Δ | <1.0a | <0.3a | 5 |
| FOL1 + pGALS:FOL1 | 61.7 ± 20 | 43.8 ± 15 | 60 |
| E. coli strain | |||
| XL1Blue | 73.8 ± 10 | 61.4 ± 15 | 185 |
| XL1Blue + ptac:FOL1 | 364.0 ± 25 | 310.7 ± 25 | 1714 |
The specific enzyme activity assays were performed using protein extracts from E. coli or yeast. E. coli XL1Blue was assayed without plasmid (control) and was transformed with pSH51 carrying the yeast FOL1 gene under control of the tac promoter (ptac-FOL1). Yeast strains that were derived from the same genetic back ground were grown in media complemented with 1 mg/ml folinic acid. Haploid CEN.PK2-1C carries a FOL1+ wt gene (FOL1), whereas YUG1 is deleted for FOL1 (fol1Δ). Strain YUG3 expresses FOL1 via the GALS promoter on a plasmid (FOL1 + pGALS-FOL1; Mumberg et al., 1994).
a
The levels were below the detection level of the assay