Pseudomonas pseudoalcaligenes KF707 grown with biphenyl expresses a cytochrome caa(3) oxidase that uses cytochrome c(4) as electron donor

Combining peroxidase activity-based heme staining (TMBZ/SDS/PAGE) with mass spectrometry analyses (Nano LC-MS/MS) of protein extracts from wild-type and appropriate mutants, we provide evidence that the polychlorinated biphenyl degrader Pseudomonas pseudoalcaligenes KF707 primarily expresses a caa3-type cytochrome c oxidase (caa3-Cox) using cytochrome (cyt) c4as an electron donor in cells grown with biphenyl versus glucose as the sole carbon source. Homology modeling of KF707 caa3-Cox using the three-dimensional structure of that from Thermus thermophilus highlights multiple similarities and differences between the proton channels in subunit I of the aa3- and caa3-Cox of Paracoccus and Thermus spp., respectively. To our knowledge, this is the first report demonstrating the presence of a caa3-Cox using cyt c4as an electron donor in a Pseudomonas species.