TABLE 2.
Cytochrome cbb3 oxidase activity in R. capsulatus strains grown under different conditionsa
| Strain | % Cytochrome cbb3 oxidase activity
|
|||||
|---|---|---|---|---|---|---|
| Aerobic
|
Semiaerobic
|
Anaerobic-photosynthetic
|
||||
| O2 uptake | cyt c oxidation | O2 uptake | cyt c oxidation | O2 uptake | cyt c oxidation | |
| MT1131 (wild type) | 100 | 100 | 100 | 100 | 100 | 100 |
| GK32 (ΔccoNO) | <1 | <1 | <1 | <1 | <1 | <1 |
| GK32/pRK415 (empty vector) | <1 | <1 | <1 | <1 | <1 | <1 |
| GK32/pOX15 (ccoNOQP in pRK415) | 262 | 240 | 290 | 270 | 315 | 254 |
| GK32/pAP4 (ccoNOP in pRK415) | 61 | 68 | 53 | 65 | 59 | 47 |
| M7G (ccoP269) | NT | NT | 5 | 3 | NT | NT |
| M7G/pAP4 (ccoNOP in pRK415) | NT | NT | 80 | 90 | NT | NT |
Cytochrome cbb3 oxidase activity in R. capsulatus membranes (ICM) was analyzed by either measuring oxygen uptake or measuring horse heart cyt c oxidation. At least three independent measurements were performed. The activity of wild-type MT1131 membranes grown under the indicated conditions was set as 100%. For O2 uptake measurements, this corresponds to 680 nmol of O2/mg of protein·h (aerobic conditions), to 1,322 nmol of O2/mg of protein·h (semiaerobic conditions), and to 115 nmol of O2/mg of protein·h (anaerobic-photosynthetic conditions). For cyt c oxidations, 100% activity corresponds to 1,500 nmol of cyt c/mg of protein·h (aerobic conditions), to 2,745 nmol of cyt c/mg of protein·h (semiaerobic conditions), and to 140 nmol of cyt c/mg of protein·h (anaerobic-photosynthetic conditions). NT, not tested.