| Summary: | The family of Nramp (natural resistance-associated macrophage protein) metal ion transporter functions in diverse organisms from bacteria to humans. <i>Acidithiobacillus ferrooxidans</i> (<i>At. ferrooxidans</i>) is a Gram-negative bacterium that lives at pH 2 in high concentrations of soluble ferrous ion (600 mM). The AFE_2126 protein of <i>At. ferrooxidans</i> of the Dachang Copper Mine (DC) was analyzed by bioinformatics software or online tools, showing that it was highly homologous to the Nramp family, and its subcellular localization was predicted to locate in the cytoplasmic membrane. Transcriptional study revealed that AFE_2126 was expressed by Fe<sup>2+</sup>-limiting conditions in <i>At. ferrooxidans</i> DC. It can be concluded that the AFE_2126 protein may function in ferrous ion transport into the cells. Based on the <i>Δ</i>pH of the cytoplasmic membrane between the periplasm (pH 3.5) and the cytoplasm (pH 6.5), it can be concluded that Fe<sup>2+</sup> is transported in the direction identical to that of the H<sup>+</sup> gradient. This study indirectly confirmed that the function of Nramp in <i>At. ferrooxidans</i> DC can transport divalent iron ions.
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