TABLE 4.
Effect of class I, class II, class III, and class IV mutations in DcuS on the fumarate and citrate sensitivities of DcuS-dependent expression of dcuB′-′lacZ
| Mutanta | Protein (mutation) | Class (site in DcuS) |
dcuB′-′lacZ fusion β-galactosidase activity (Miller units)b
|
Fumarate/citrate ratioc | ||
|---|---|---|---|---|---|---|
| No addition | + Fumarate | + Citrate | ||||
| IMW260d(pdcuS+) (wild type) | DcuS | Wild type | 17 | 189 | 89 | 2.1 |
| IMW260(pMW352) | DcuS(F149K A164S) | Class I (ligands in C1) | 4 | 42 | 1 | 42.0 |
| IMW260(pMW345) | DcuS(F149K) | Class I (ligands in C1) | 3 | 110 | 5 | 22.0 |
| IMW260(pMW354) | DcuS(F141S) | Class II (ligands in C3) | 7 | 159 | 9 | 17.7 |
| IMW260(pMW409) | DcuS(F149K A164S F141S) | Class I + II | 2 | 4 | 4 | 1 |
| IMW260(pMW353) | DcuS(T101G F120M I125S) | Class III (size of C1/C2) | 5 | 1 | 58 | 0.02 |
| IMW260(pMW372) | DcuS(T101G F120M I125S F149K A164S) | Class I + III | 2 | 2 | 27 | 0.07 |
| IMW260(pMW410) | DcuS(T101G F120M I125S F141S) | Class II + III | 3 | 3 | 4 | 0.75 |
| IMW260(pMW355) | DcuS(Q159V) | Class IV (access binding site) | 8 | 212 | 23 | 9.2 |
| IMW260(pMW356) | DcuS(Q159V M103A) | Class IV (access binding site) | 5 | 194 | 17 | 11.4 |
a
Anaerobic growth of the transformed bacteria in glycerol-plus-DMSO medium in the presence of fumarate or citrate. Other conditions are as in Fig. 4.
b
β-Galactosidase activities for four replicates each in two independent growth experiments with three cultures each (deviation, ≤15%).
c
Ratio of fumarate- and citrate-induced β-galactosidase activities.
d
dcuS deletion strain (IMW260).