Uranium is a naturally occurring radionuclide. Its redistribution, primarily due to human activities, can have adverse effects on human and non-human biota, which poses environmental concerns. The molecular mechanisms of uranium tolerance and the cellular response induced by uranium exposure in bacteria are not yet fully understood. Here, we carried out a comparative analysis of four actinobacterial strains isolated from metal and radionuclide-rich soils that display contrasted uranium tolerance phenotypes. Comparative proteogenomics showed that uranyl exposure affects 39–47% of the total proteins, with an impact on phosphate and iron metabolisms and membrane proteins. This approach highlighted a protein of unknown function, named UipA, that is specific to the uranium-tolerant strains and that had the highest positive fold-change upon uranium exposure. UipA is a single-pass transmembrane protein and its large C-terminal soluble domain displayed a specific, nanomolar binding affinity for UO₂²⁺ and Fe³⁺. ATR-FTIR and XAS-spectroscopy showed that mono and bidentate carboxylate groups of the protein coordinated both metals. The crystal structure of UipA, solved in its apo state and bound to uranium, revealed a tandem of PepSY domains in a swapped dimer, with a negatively charged face where uranium is bound through a set of conserved residues. This work reveals the importance of UipA and its PepSY domains in metal binding and radionuclide tolerance.

铀是一种天然存在的放射性核素。它的重新分布，主要是由于人类活动，可能对人类和非人类生物群产生不利影响，从而引起环境问题。铀耐受性的分子机制和铀暴露在细菌中引起的细胞反应尚不完全清楚。在这里，我们对从富含金属和放射性核素的土壤中分离出的四种放线菌菌株进行了比较分析，这些菌株显示出对比的铀耐受表型。比较蛋白质组学表明，铀酰暴露会影响总蛋白质的 39-47%，并对磷酸盐和铁代谢以及膜蛋白产生影响。这种方法突出了一种功能未知的蛋白质，名为 UipA，这是耐铀菌株特有的，并且在铀暴露时具有最高的正倍数变化。UipA 是一种单次跨膜蛋白，其大的 C 末端可溶性结构域显示出对 UO 的特定纳摩尔结合亲和力₂ ²⁺和铁³⁺。ATR-FTIR 和 XAS 光谱显示蛋白质的单齿和双齿羧酸盐基团与两种金属配位。UipA 的晶体结构以其 apo 状态解析并与铀结合，揭示了交换二聚体中的串联 PepSY 结构域，具有带负电的面，其中铀通过一组保守残基结合。这项工作揭示了 UipA 及其 PepSY 结构域在金属结合和放射性核素耐受性方面的重要性。