Evidence for a Key Role of Cytochrome bo3 Oxidase in Respiratory Energy Metabolism of Gluconobacter oxydans

Abstract

The obligatory aerobic acetic acid bacterium Gluconobacter oxydans oxidizes a variety of substrates in the periplasm by membrane-bound dehydrogenases, which transfer the reducing equivalents to ubiquinone. Two quinol oxidases, cytochrome bo 3 and cytochrome bd, then catalyze transfer of the electrons from ubiquinol to molecular oxygen. In this study, mutants lacking either of these terminal oxidases were characterized. Deletion of the cydAB genes for cytochrome bd had no obvious influence on growth, whereas the lack of the cyoBACD genes for cytochrome bo 3 severely reduced the growth rate and the cell yield. Using a respiration activity monitoring system and adjusting different levels of oxygen availability, hints of a low-oxygen affinity of cytochrome bd oxidase were obtained, which were supported by measurements of oxygen consumption in a respirometer. The H ؉ /O ratio of the ⌬cyoBACD mutant with mannitol as the substrate was 0.56 ؎ 0.11 and more than 50% lower than that of the reference strain (1.26 ؎ 0.06) and the ⌬cydAB mutant (1.31 ؎ 0.16), indicating that cytochrome bo 3 oxidase is the main component for proton extrusion via the respiratory chain. Plasmid-based overexpression of cyoBACD led to increased growth rates and growth yields, both in the wild type and the ⌬cyoBACD mutant, suggesting that cytochrome bo 3 might be a rate-limiting factor of the respiratory chain.

The aerobic respiratory chain of Pseudomonas aeruginosa cultured in artificial urine media: Role of NQR and terminal oxidases

“…well as in Gluconobacter oxydans [79], CYO was also found to be the main terminal oxidase, suggesting a common evolutionary or physiologic trend among prokaryotes.…”

Complete Genome Sequencing and Comparative Genomic Analysis of the Thermotolerant Acetic Acid Bacterium, <i>Acetobacter pasteurianus</i> SKU1108, Provide a New Insight into Thermotolerance

“…These genes were also conserved in complete genomes of the strains 386B and NBRC 3283. The respiratory chains of Acetobacter species are known to play crucial roles in energy metabolism (24, 27). Therefore, the gene repertoires of respiratory chains were investigated.…”

Utilization of d -Lactate as an Energy Source Supports the Growth of Gluconobacter oxydans

“…Membrane-bound GOX1253 transfers 2 mol of electrons to ubiquinone when oxidizing 1 mol of D-lactate. Two quinol oxidases, cytochrome bo3 and cytochrome bd, then catalyze the transfer of electrons from the reduced ubiquinone to molecular oxygen, which is accompanied by the generation of proton motive force (1,2,41). Subsequently, the electrochemical proton gradient is used to generate ATP via an F 1 F o -type ATP synthase (2).…”