Table 2.
R. sphaeroides Cyt cy is able to support electron transfer from the Cyt bc1 complex to the Cyt cbb3 oxidase in R. capsulatus
| Strain | Electron carrier (Cyt c2 or Cyt cy) | Ps | Res, min | Myx178 |
|---|---|---|---|---|
| MT1131 | Cyt c2Rc + Cyt cyRc | +† | +, 142 | + |
| pRK415/M6G-G4/S4 | Cyt cyRc | + | +, 199 | − |
| pHM13/SL3‡ | Cyt cyRs | −† | +, 344 | − |
| pHM14/SL3 | Cyt c2Rc | + | +, 265 | − |
| pHM8/SL3 | Cyt MA-c2Rc | + | +, 264 | − |
| pHM100/SL3§ | Cyt c exchange chimera | − | +, 321 | − |
Myx corresponds to respiratory growth in the presence of 10 μM myxothiazol in MPYE medium.
MT1131 has a doubling time of approximately 120 min and forms colonies 1.7–1.9 mm in diameter after 2 days of incubation on MPYE medium under the growth conditions used. “+” and “−” indicate Ps growth similar to that of MT1131 on solid medium and no visible colony formation after 5 days of incubation under the same conditions, respectively. Growth rates were not redetermined in SL3 (Qox−) background, because, in the more appropriate R. capsulatus strain FJ2 (Cyt c2− and Cyt cy−), plasmid-borne Cyt cyRc, Cyt c2Rc, and its membrane-bound derivative (Cyt MA-c2Rc) support Ps growth in MPYE medium with doubling times of 205, 137, and 154 min, respectively, whereas Cyt cyRs (pHM13) and cyt c exchange chimera (pHM100) do not confer any appreciable Ps growth.
SL3 was obtained by introducing Δ(cycY∷spe) allele into the R. capsulatus strain M6G-G4/S4 (Qox− Cyt c2−) carrying the desired electron carrier on a plasmid, as described in Materials and Methods.
No SpeR derivative of pHM127/M6G-G4/S4 carrying the linker-anchor exchange chimera was obtained on introduction of cycY∷spe under Res or Ps growth conditions, unlike pHM100/M6G-G4/S4 (or pHM126/M6G-G4/S4; not shown) carrying the Cyt c exchange chimera.