Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA.
Biometals. 2023 Dec;36(6):1285-1294. doi: 10.1007/s10534-023-00517-6. Epub 2023 Jun 21.
Escherichia coli ferric uptake regulator (Fur) binds a [2Fe-2S] cluster, not a mononuclear iron, when the intracellular free iron content is elevated in E. coli cells. Here we report that the C-terminal domain (residues 83-148) of E. coli Fur (Fur-CTD) is sufficient to bind the [2Fe-2S] cluster in response to elevation of the intracellular free iron content in E. coli cells. Deletion of gene fur in E. coli cells increases the intracellular free iron content and promotes the [2Fe-2S] cluster binding in the Fur-CTD in the cells grown in LB medium under aerobic growth conditions. When the Fur-CTD is expressed in wild type E. coli cells grown in M9 medium supplemented with increasing concentrations of iron, the Fur-CTD also progressively binds a [2Fe-2S] cluster with a maximum occupancy of about 36%. Like the E. coli Fur-CTD, the CTD of the Haemophilus influenzae Fur can also bind a [2Fe-2S] cluster in wild type E. coli cells grown in M9 medium supplemented with increasing concentrations of iron, indicating that binding of the [2Fe-2S] cluster in the C-terminal domain is highly conserved among Fur proteins. The results suggest that the Fur-CTD can be used as a physiological probe to assess the intracellular free iron content in bacteria.
当大肠杆菌细胞内游离铁含量升高时，大肠杆菌铁摄取调节蛋白（Fur）结合的是[2Fe-2S]簇，而不是单核铁。在这里，我们报告大肠杆菌 Fur 的 C 端结构域（残基 83-148）（Fur-CTD）足以结合[2Fe-2S]簇，以响应大肠杆菌细胞内游离铁含量的升高。在有氧生长条件下，LB 培养基中生长的大肠杆菌细胞中 fur 基因缺失会增加细胞内游离铁含量，并促进细胞中 Fur-CTD 结合[2Fe-2S]簇。当 Fur-CTD 在 M9 培养基中生长的野生型大肠杆菌细胞中表达，并补充不同浓度的铁时，Fur-CTD 也逐渐结合[2Fe-2S]簇，最大占有率约为 36%。与大肠杆菌 Fur-CTD 一样，流感嗜血杆菌 Fur 的 CTD 也可以在补充不同浓度铁的 M9 培养基中生长的野生型大肠杆菌细胞中结合[2Fe-2S]簇，表明 Fur 蛋白的 C 端结构域结合[2Fe-2S]簇具有高度保守性。这些结果表明，Fur-CTD 可用作生理探针来评估细菌细胞内游离铁含量。
