Fig 1.

cbb₃-Cox subunit compositions and NADI phenotypes of the wild-type strain and the ccoA mutant and its derivatives. (A) Amounts of CcoP and CcoO subunits of cbb₃-Cox in response to Cu²⁺ supplementation. Membrane-associated c-type cytochrome profiles are shown for the wild-type (MT1131) and ΔccoA (SE8) strains grown in MPYE medium supplemented with 0, 5, 10, or 25 μM Cu²⁺ under respiratory conditions at 35°C. Chromatophore membrane proteins (50 μg) were separated using 16.5% SDS-PAGE, and c-type cytochromes were visualized by TMBZ staining (see Materials and Methods). CcoO and CcoP are the c-type cytochrome subunits of cbb₃-Cox, and c₁ and c_y refer to the cytochrome c₁ subunit of cytochrome bc₁ and the membrane-attached electron carrier cytochrome c_y, respectively. (B) Ps growth and NADI phenotypes of Cu-unresponsive mutants XJ3 and XJ11. The wild type (MT1131), the ΔccoA mutant (SE8), and Cu-unresponsive ΔccoA derivatives XJ3 (ccmA3) and XJ11 (ccmF11) were grown on MPYE medium-containing plates under Ps and respiratory conditions, with 5 μM Cu²⁺ where indicated. The blue staining seen in the upper left quadrangle of each plate grown under respiratory conditions depicts the NADI⁺ phenotype of the wild-type strain.