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Disruption of manganese ions [Mn(II)] transporter genes DR1709 or DR2523 in extremely radio-resistant bacterium Deinococcus radiodurans.

OBJECTIVE
The primary objective of this study was to identify whether the manganese ions [Mn(II)] transporter genes DR1709 and DR2523 played roles in Deinococcus radiodurans's radiation resistance. The second objective was to study the relationships among manganese ions, manganese ions transporter genes and the bacterial radioresistance.


METHODS
We constructed mutants of DR1709 and DR2523. The wild type and the mutants were treated with UV and hydrogen peroxide (H2O2). The survival fractions of the three strains were analyzed.


RESULTS
Disruption of DR2523 hardly affected the growth of D. radiodurans in tryptone-glucose-yeast extract (TGY) broth. But at each site of the logarithmic stages,the OD600 values of DR1709 mutant (M1709) were much lower than those of the wild type. After being treated with H2O2 and UV,the survival rates of M1709 cells at each dose were much lower than those of the wild type. However,the DR2523 mutant (M2523) and wild type had the similar appearance after being treated with H2O2 and UV, though the wild type had the higher survival than M2523.


CONCLUSION
DR1709 and DR2523 could protect D. radiodurans from irradiation and superoxide radicals. In D. radiodurans, transporting Mn(II) from the medium was possibly controlled by several different steps. The roles of DR2523 might be partially substituted by DR2283 and/or DR2284, while no other genes could exercise the similar function as DR1709.