FIG. 3.

Expression of respiratory proteins in P. pantotrophus wild type and narR::Ω. Strains were grown anaerobically with nitrite as the electron acceptor; 20-ml cultures were harvested by centrifugation, resuspended in 1 ml of 10 mM Tris-HCl (pH 8), and sonicated. Extracts were separated by SDS-PAGE (20 μg of protein in each lane) and Western blotted with antibodies raised to nitrous oxide reductase (A) and pseudoazurin (B) or stained for proteins containing covalently attached heme (C). Heme proteins cytochrome cd₁ nitrite reductase and the c-heme-containing subunits of cytochrome cbb₃ oxidase are marked. Lanes 1 and 3 contain extracts from P. pantotrophus wild type; lanes 2 and 4 contain extracts from P. pantotrophus narR::Ω.