Porphyromonas gingivalis FeoB1 is a ferrous iron transporter. Analysis of parental and feoB1-deficient strains of the periodontal pathogen revealed that the feoB1-deficient mutant strain had an increased ability to survive oxidative stress. Specifically, survival of the mutant strain was increased 33% with exposure to peroxide and 5% with exposure to atmospheric oxygen compared to the parental strain. Interestingly, the ability to survive intracellularly also increased fivefold in the case of the feoB1-deficient mutant. Our data suggest that although the FeoB1 protein is required for ferrous iron acquisition in P. gingivalis, it also has an adverse effect on survival of the bacterium under oxidative stress conditions. Finally, we show that feoB1 expression is not iron dependent and is dramatically reduced in the presence of host cells, consistent with the observed deleterious role it plays in bacterial survival.
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