TABLE 1.
Properties of Y302X mutants under aerobic conditions
| Strain | Wild type | Y302A | Y302C | Y302F | Y302S | Y302V |
|---|---|---|---|---|---|---|
| Relevant phenotypea | Ps+ | Ps+ | Ps+ | Ps+ | Ps+ | Ps+ |
| Membrane protein content (mg/ml) | 13.4 ± 0.7d | 12.3 ± 0.5 | 13.4 ± 0.9 | 14.3 ± 0.6 | 15.5 ± 1.8 | 12.7 ± 0.5 |
| Membrane cytochrome b content (nmol/mg)b | 2.4 ± 0.2 | 2.7 ± 0.2 | 2.6 ± 0.2 | 2.5 ± 0.2 | 2.4 ± 0.2 | 2.7 ± 0.2 |
| Membrane cytochrome c content (nmol/mg)b | 1.7 ± 0.1 | 1.7 ± 0.1 | 1.7 ± 0.2 | 1.4 ± 0.2 | 1.6 ± 0.2 | 1.6 ± 0.2 |
| Relative cytochrome c reductase activity (%)c | ||||||
| No inhibitor | 100 | 15.4 ± 1.4 | 14.8 ± 2.9 | 77.4 ± 8.4 | 4.0 ± 1.3 | 41.6 ± 4.3 |
| Stigmatellin | 0.4 ± 0.2 | 0.3 ± 0.1 | 0.4 ± 0.1 | 0.3 ± 0.1 | 0.3 ± 0.1 | 0.3 ± 0.1 |
| Myzothiazol | 0.8 ± 0.1 | 5.6 ± 0.1 | 1.6 ± 0.1 | 1.3 ± 0.4 | 4.4 ± 0.4 | 1.8 ± 0.1 |
| Famoxadone | 0.2 ± 0.1 | 0.2 ± 0.1 | 0.1 ± 0.1 | 0.2 ± 0.1 | 0.1 ± 0.1 | 0.2 ± 0.1 |
| Antimycin A | 0.3 ± 0.1 | 0.8 ± 0.1 | 1.4 ± 1.0 | 3.7 ± 1.2 | 9.7 ± 1.9 | 7.7 ± 3.0 |
a Ps+ refers to anaerobic photosynthetic (−O2) growth ability.
b Cytochromes c and b contents of membranes were determined using optical redox difference spectra.
c Cytochrome bc1 activity refers to the 2,3-dimethoxy-5-methyl-6-decyl-1,4-benzohydroquinone (DBH2): cytochrome c reductase activity expressed as a percentage of the wild-type activity, which was approximately 3.5 μmol of cytochrome c reduced min−1 mg of protein−1 of membranes prepared in the presence of air using aerobically grown cells. Each assay was conducted at least in triplicate.
d The data are the means ± standard deviations.