MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Tianshuinanlu #222, Lanzhou, 730000, Gansu, People's Republic of China.
Ecotoxicology. 2014 May;23(4):726-33. doi: 10.1007/s10646-014-1201-2. Epub 2014 Feb 8.
The sulfate reducing bacterium Desulfovibrio alaskensis strain G20 can grow in lactate sulfate medium with up to 4 mM uranyl acetate. In order to identify the genes that are required for the growth of strain G20 at toxic levels of uranium(VI) (U(VI)), 5,760 transposon insertion mutants were screened for U(VI) resistance defects, and 24 of them showed loss of U(VI) resistance in lactate sulfate medium with 2 mM uranyl acetate. In the 24 mutants, 23 genes were disrupted by transposon insertions, and one transposon is located in a non-coding region. In the ten mutants that were completely inhibited by 2 mM uranyl acetate, the disrupted genes are involved in DNA repair, rRNA methylation, regulation of expression and RNA polymerase renaturation. The remaining 14 mutants showed partial inhibition of growth by 2 mM U(VI), in which the disrupted genes participate in DNA repair, regulation of transcription, membrane transport, etc. In addition, none except one of these 24 mutants showed loss in its ability to reduce U(VI) to U(IV) in the washed cell test. These results altogether suggest that U(VI) toxicity mainly involves damage to nucleic acids and proteins.
脱硫弧菌（Desulfovibrio alaskensis）菌株 G20 可以在含有高达 4mM 醋酸铀酰的乳酸硫酸盐培养基中生长。为了鉴定在铀(VI)（U(VI)）毒性水平下生长所需的基因，筛选了 5760 个转座子插入突变体，以寻找 U(VI)抗性缺陷，其中 24 个在含有 2mM 醋酸铀酰的乳酸硫酸盐培养基中表现出 U(VI)抗性丧失。在这 24 个突变体中，23 个基因被转座子插入所破坏，一个转座子位于非编码区。在完全被 2mM 醋酸铀酰抑制的 10 个突变体中，被破坏的基因参与 DNA 修复、rRNA 甲基化、表达调控和 RNA 聚合酶复性。其余 14 个突变体在 2mM U(VI)存在下表现出部分生长抑制，其中被破坏的基因参与 DNA 修复、转录调控、膜转运等。此外，除了一个突变体外，这些 24 个突变体在洗细胞试验中均未显示出丧失将 U(VI)还原为 U(IV)的能力。这些结果表明，U(VI)的毒性主要涉及核酸和蛋白质的损伤。
