Bruch E M, de Groot A, Un S, Tabares L C
From the Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, 91191 Gif-sur-Yvette, France.
Metallomics. 2015 May;7(5):908-16. doi: 10.1039/c5mt00009b. Epub 2015 Mar 26.
D. radiodurans accumulates large quantities of Mn(II), which is believed to form low molecular weight complexes with phosphate and metabolites that protect D. radiodurans from radiation damage. The concentration of Mn(II) species in D. radiodurans during the exponential and stationary phase was determined using high-field EPR and biochemical techniques. In the exponential growth phase cells a large fraction of the manganese was in the form of Mn(II)-orthophosphate complexes. By contrast, the intracellular concentration of these compounds in stationary phase cells was less than 16 μM, while that of Mn superoxide dismutase was 320 μM and that of another, yet unidentified, Mn(II) protein was 250 μM. Stationary cells were found to be equally resistant to irradiation as the exponential cells in spite of having significant lower Mn(II)-orthophosphate concentrations. Gamma irradiation induced no changes in the Mn(II) speciation. During stationary growth phase D. radiodurans favours the production of the two Mn-proteins over low molecular weight complexes suggesting that the latter were not essential for radio-resistance at this stage of growth.
耐辐射球菌会积累大量的二价锰（Mn(II)），据信二价锰会与磷酸盐和代谢物形成低分子量复合物，从而保护耐辐射球菌免受辐射损伤。利用高场电子顺磁共振（EPR）和生化技术测定了指数生长期和稳定期耐辐射球菌中二价锰物种的浓度。在指数生长期的细胞中，大部分锰以二价锰-正磷酸盐复合物的形式存在。相比之下，稳定期细胞中这些化合物的细胞内浓度低于16μM，而锰超氧化物歧化酶的浓度为320μM，另一种尚未鉴定的二价锰蛋白的浓度为250μM。尽管稳定期细胞中二价锰-正磷酸盐浓度显著较低，但发现其对辐射的抗性与指数生长期细胞相同。γ射线照射未引起二价锰物种的变化。在稳定生长期，耐辐射球菌更倾向于产生这两种锰蛋白而非低分子量复合物，这表明在这个生长阶段，低分子量复合物对于抗辐射并非必不可少。
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