Differences in two Pseudomonas aeruginosa cbb3 cytochrome oxidases.
Bacterial cytochrome cbb3 oxidases are members of the haeme-copper oxidase superfamily that are important for energy conservation by a variety of proteobacteria under oxygen-limiting conditions. The opportunistic pathogen Pseudomonas aeruginosa is unusual in possessing two operons that each potentially encode a cbb3 oxidase (cbb3-1 or cbb3-2). Our results demonstrate that, unlike typical enzymes of this class, the cbb3-1 oxidase has an important metabolic function at high oxygen tensions. In highly aerated cultures, cbb3-1 abundance and expression were greater than that of cbb3-2, and only loss of cbb3-1 influenced growth. Also, the activity of cbb3-1, not cbb3-2, inhibited expression of the alternative oxidase CioAB and thus influenced a signal transduction pathway much like that found in the alpha-proteobacterium Rhodobacter sphaeroides. Cbb3-2 appeared to play a more significant role under oxygen limitation by nature of its increased abundance and expression compared to highly aerated cultures, and the regulation of the cbb3-2 operon by the putative iron-sulphur protein Anr. These results indicate that each of the two P. aeruginosa cbb3 isoforms have assumed specialized energetic and regulatory roles.
Comolli
James C
JC
Department of Bacteriology, University of Wisconsin-Madison, 420 Henry Mall, Madison, WI 53706, USA.
Donohue
Timothy J
TJ
D000332:Aerobiosis; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D003580:Cytochromes / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D003576:Electron Transport Complex IV / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D023061:Gene Order; D005798:Genes, Bacterial; D017930:Genes, Reporter; D009876:Operon; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D003580:Cytochromes; D004268:DNA-Binding Proteins; D015534:Trans-Activators; C072908:ANR protein, Pseudomonas aeruginosa; C414443:cbb3 oxidase; D003576:Electron Transport Complex IV; D001616:beta-Galactosidase; D010100:Oxygen