| Description | Bacteroides fragilis, an opportunistic pathogen and commensal bacterium in the gut, is one the most
aerotolerant species among strict anaerobes. However, the mechanisms that control gene regulation in
response to oxidative stress are not completely understood. In this study, we show that the MarR type
regulator, BmoR, regulates the expression of genes involved in the homeostasis of intracellular redox
state. Transcriptome analysis showed that absence of BmoR leads to altered expression in total of 167
genes. Sixteen of these genes had a 2-fold or greater change in their expression. Most of these genes
are related to LPS biosynthesis and carbohydrates metabolism, but there was a signifcant increase
in the expression of genes related to the redox balance inside the cell. A pyridine nucleotide-disulfde
oxidoreductase located directly upstream of bmoR was shown to be repressed by direct binding of
BmoR to the promoter region. The expression of two other genes, coding for a thiosulphate:quinoneoxidoreductase and a thioredoxin, are indirectly afected by bmoR mutation during oxygen exposure.
Phenotypic assays showed that BmoR is important to maintain the thiol/disulfde balance in the cell,
confrming its relevance to B. fragilis response to oxidative stress. | en_US |
