Metabolic pathways in cancer cells typically become reprogrammed to support unconstrained proliferation. These abnormal metabolic states are often accompanied by accumulation of high concentrations of ATP in the cytosol, a phenomenon known as the Warburg Effect. However, how high concentrations of ATP relate to the functional state of proteins is poorly understood. Here, we comprehensively studied the influence of ATP levels on the functional state of the human enzyme, uridine phosphorylase I (hUP1), which is responsible for activating the chemotherapeutic pro‐drug, 5‐fluorouracil. We found that elevated levels of ATP decrease the stability of hUP1, leading to the loss of its proper folding and function. We further showed that the concentration of hUP1 exerts a critical influence on this ATP‐induced destabilizing effect. In addition, we found that ATP interacts with hUP1 through a partially unfolded state and accelerates the rate of hUP1 unfolding. Interestingly, some structurally similar metabolites showed similar destabilization effects on hUP1. Our findings suggest that metabolites can alter the folding and function of a human protein, hUP1, through protein destabilization. This phenomenon may be relevant in studying the functions of proteins that exist in the specific metabolic environment of a cancer cell.

中文翻译：

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代谢物调节人尿苷磷酸化酶 I 的功能状态。

癌细胞中的代谢途径通常会重新编程以支持不受限制的增殖。这些异常代谢状态通常伴随着细胞质中高浓度 ATP 的积累，这种现象被称为 Warburg 效应。然而，人们对高浓度的 ATP 与蛋白质功能状态的关系知之甚少。在这里，我们全面研究了 ATP 水平对人体酶尿苷磷酸化酶 I (hUP1) 功能状态的影响，该酶负责激活化疗前药 5-氟尿嘧啶。我们发现升高的 ATP 水平会降低 hUP1 的稳定性，导致其正确折叠和功能的丧失。我们进一步表明，hUP1 的浓度对这种 ATP 诱导的不稳定效应产生了关键影响。此外，我们发现 ATP 通过部分展开状态与 hUP1 相互作用并加速 hUP1 展开的速度。有趣的是，一些结构相似的代谢物对 hUP1 显示出相似的去稳定作用。我们的研究结果表明，代谢物可以通过蛋白质不稳定来改变人类蛋白质 hUP1 的折叠和功能。这种现象可能与研究存在于癌细胞特定代谢环境中的蛋白质的功能有关。