Abstract
R. sphaeroides can grow both under respiration and photosynthesis conditions. Elimination of reactive oxygen species (ROS), therefore must be critical for their growth. In this study, we focused on R. sphaeroides peroxiredoxin (Prx) to get insight into the antioxidative stress system of this bacterium, since Prx is reported as an important antioxidant protein for various organisms.
On the genome of R. sphaeroides, two genes encoding TypeII Prx and PrxQ have been assigned. Both the recombinant Prxs could catalyze the reduction of various ROS using thioredoxin. Growth rate of PrxQ disruptant was slower than that of wild type. In addition, the accumulation of the photopigment synthesis in the disruptant was significantly lower than that of wild type. These results suggest that PrxQ functions as a main quencher for the ROS in this bacterium, and the redox balance in the cell must affect the regulation of photopigment synthesis in this bacterium.
