| Summary: | <p>Abstract</p> <p>Background</p> <p><it>Deinococcus radiodurans </it>accumulates high levels of manganese ions, and this is believed to be correlated with the radiation resistance ability of this microorganism. However, the maintenance of manganese ion homeostasis in <it>D. radiodurans </it>remains to be investigated.</p> <p>Results</p> <p>In this study, we identified the manganese efflux protein (MntE) in <it>D. radiodurans</it>. The null mutant of <it>mntE </it>was more sensitive than the wild-type strain to manganese ions, and the growth of the <it>mntE </it>mutant was delayed in manganese-supplemented media. Furthermore, there was a substantial increase in the <it>in vivo </it>concentration of manganese ions. Consistent with these characteristics, the <it>mntE </it>mutant was more resistant to H<sub>2</sub>O<sub>2</sub>, ultraviolet rays, and γ-radiation. The intracellular protein oxidation (carbonylation) level of the mutant strain was remarkably lower than that of the wild-type strain.</p> <p>Conclusions</p> <p>Our results indicated that <it>dr1236 </it>is indeed a <it>mntE </it>homologue and is indispensable for maintaining manganese homeostasis in <it>D. radiodurans</it>. The data also provide additional evidence for the involvement of intracellular manganese ions in the radiation resistance of <it>D. radiodurans</it>.</p>
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