TABLE 2.
Regulation of GBase synthesis
| Enzyme source | GBase activitya (U/mg of protein)
|
|||
|---|---|---|---|---|
| Glu | 4-GB | Glu + 4-GB | 3-GP | |
| PAO1 (wild type) | <0.1 | 4.7 ± 0.4 | 3.1 ± 0.2 | <0.1 |
| PAO4156 (gbuA9005) | <0.1 | ng | <0.1 | nd |
| PAO4508 (gbuR::Gm) | <0.1 | ng | <0.1 | nd |
| PAO4518 (gbuA::Gm) | <0.1 | ng | <0.1 | nd |
| PAO4156/pYl1011 (Ptac::gbuA) | <0.1 | 5.7 ± 0.2 | nd | nd |
| PAO4156/pYl1011 (Ptac::gbuA) | 1.4 ± 0.1b | 10.2 ± 0.5b | nd | nd |
a
Cells were cultured to mid-log phase (OD600 = 0.5) in MMP containing the indicated supplements as sole C and N sources at 20 mM. Cell extracts were prepared and enzymes were assayed as described in Materials and Methods. Glu, glutamate; 4-GB, 4-guanidinobutyrate; 3-GP, 3-guanidinopropionate.
b
When cultures reached an OD600 of 0.5, 0.5 mM IPTG was added, and incubation was continued for an additional 2 h. Values are averages of three independent measurements with standard errors. ng, no growth; nd, not determined.