Key Laboratory for Nuclear-Agricultural Sciences of Chinese Ministry of Agriculture and Zhejiang Province, Institute of Nuclear-Agricultural Sciences, Zhejiang University, 310029, Hangzhou, PR China.
BMC Microbiol. 2010 Dec 14;10:319. doi: 10.1186/1471-2180-10-319.
Deinococcus radiodurans 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 D. radiodurans remains to be investigated.
In this study, we identified the manganese efflux protein (MntE) in D. radiodurans. The null mutant of mntE was more sensitive than the wild-type strain to manganese ions, and the growth of the mntE mutant was delayed in manganese-supplemented media. Furthermore, there was a substantial increase in the in vivo concentration of manganese ions. Consistent with these characteristics, the mntE mutant was more resistant to H2O2, 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.
Our results indicated that dr1236 is indeed a mntE homologue and is indispensable for maintaining manganese homeostasis in D. radiodurans. The data also provide additional evidence for the involvement of intracellular manganese ions in the radiation resistance of D. radiodurans.
耐辐射球菌积累了大量的锰离子，这被认为与这种微生物的辐射抗性能力有关。然而，耐辐射球菌中锰离子的动态平衡的维持还需要进一步研究。
在本研究中，我们在耐辐射球菌中鉴定了锰外排蛋白（MntE）。mntE 缺失突变体比野生型菌株对锰离子更敏感，并且在补充锰的培养基中生长缓慢。此外，体内锰离子浓度显著增加。与这些特征一致，mntE 突变体对 H2O2、紫外线和γ射线的抗性更强。突变菌株的细胞内蛋白质氧化（羰基化）水平明显低于野生型菌株。
我们的结果表明，dr1236 确实是 mntE 的同源物，对于维持耐辐射球菌中的锰动态平衡是不可或缺的。这些数据还为细胞内锰离子参与耐辐射球菌的辐射抗性提供了额外的证据。
