Cadmium (Cd) is a common toxic heavy metal in the environment, and bacteria have evolved different strategies against Cd-toxicity. Here, we found that marine bacterium Bacillus sp. 98 could significantly alleviate Cd-toxicity by recruiting calcium (Ca) for reducing excessive intracellular nitric oxide (NO) and enhancing iron acquisition. To investigate the underlying mechanisms, mass spectrometry-based proteomic analysis was applied to Bacillus sp. 98 after treated with Cd supplemented with or without Ca. Compared with bacterial cells treated with Cd only, the proteomic results showed that the expression level of NO synthase was markedly down-regulated, while the expression levels of NO dioxygenase, which is responsible for converting NO to nitrate, and proteins associated with iron uptake were profoundly enhanced when Ca was supplemented. Consistently, bacterial intracellular NO amount was dramatically increased after Bacillus sp. 98 was treated with Cd, and reversed to a normal level when Ca or iron was supplemented. Notably, Ca also protected bacteria against stresses from other heavy metals including Cu, Cr, Mn, Ni and Zn, and this self-protection strategy was adopted as well in zebrafish, which encourages us to develop Ca-associated products against heavy metals toxicity in the future.

中文翻译：

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钙通过减少一氧化氮的产生和增加铁的获取来保护细菌免受镉胁迫

镉 (Cd) 是环境中常见的有毒重金属，细菌已经进化出不同的策略来对抗 Cd 毒性。在这里，我们发现海洋细菌芽孢杆菌。98 可以通过招募钙 (Ca) 来减少细胞内过多的一氧化氮 (NO) 和增强铁的获取，从而显着减轻 Cd 毒性。为了研究潜在的机制，基于质谱的蛋白质组学分析被应用于芽孢杆菌sp. 98 用 Cd 添加或不添加 Ca 处理后。与仅用 Cd 处理的细菌细胞相比，蛋白质组学结果表明 NO 合酶的表达水平显着下调，而负责将 NO 转化为硝酸盐的 NO 双加氧酶和与铁吸收相关的蛋白质的表达水平显着下调。补充 Ca 后显着增强。一致地，芽孢杆菌后细菌细胞内 NO 量显着增加sp. 98 用 Cd 处理，并在补充 Ca 或铁后恢复到正常水平。值得注意的是，Ca 还保护细菌免受来自其他重金属（包括 Cu、Cr、Mn、Ni 和 Zn）的胁迫，而且斑马鱼也采用了这种自我保护策略，这鼓励我们开发 Ca 相关产品对抗重金属毒性。未来。