TABLE 2.
Enzyme activities measured in wild-type and mutant strains of B. fungorum LB400 grown on citrate and choline.
| Strain | Sp act (mU)a
|
|||||||
|---|---|---|---|---|---|---|---|---|
| Citrate
|
Cholineb
|
|||||||
| FDHc | FDH(G)d | MtdB | Mch | FDHc | FDH(G)d | MtdB | Mch | |
| Wild type | <1 | 100 | <1 | <1 | 800 | 750 | 20 | 20 |
| flhA | <1 | <1 | NDe | <1 | 700 | 750 | ND | 22 |
| fdhA | <1 | 30 | ND | <1 | <1 | 200 | ND | 23 |
| mtdB | <1 | 45 | <1 | <1 | 650 | 700 | <1 | 25 |
| flhA fdhA | <1 | <1 | <1 | <1 | 25 | 25 | ND | 22 |
| flhA mtdB | <1 | <1 | ND | <1 | 660 | 590 | ND | 24 |
| mtdB fdhA | <1 | 45 | ND | <1 | <1 | 145 | ND | 23 |
| flhA fdhA mtdB | <1 | <1 | ND | <1 | <1 | <1 | ND | 25 |
a
Specific activities are in milliunits (nanomoles of substrate converted per minute per milligram of protein). Assays were carried out in triplicate, and activity values agreed between the replicates within 15%.
b
The triple mutant is severely defective for growth on choline. To test for enzyme activities normally induced during growth on choline, cells were grown in citrate-supplemented medium, pelleted, and incubated in the presence of choline overnight.
c
FDH assay with no GSH added (see Materials and Methods).
d
FDH assay with GSH added.
e
ND, not determined.