Filamentous cable bacteria display unrivalled long-range electron transport, generating electrical currents over centimeter distances through a highly ordered network of fibers embedded in their cell envelope. The conductivity of these periplasmic wires is exceptionally high for a biological material, but their chemical structure and underlying electron transport mechanism remain unresolved. Here, we combine high-resolution microscopy, spectroscopy, and chemical imaging on individual cable bacterium filaments to demonstrate that the periplasmic wires consist of a conductive protein core surrounded by an insulating shell layer. The core proteins contain a sulfur-ligated nickel cofactor, and conductivity decreases when nickel is oxidized or selectively removed. The involvement of nickel as the active metal in biological conduction is remarkable, and suggests a hitherto unknown form of electron transport that enables efficient conduction in centimeter-long protein structures.

中文翻译：

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电缆细菌通过镍蛋白线的有效远距离传导

丝状细菌显示出无与伦比的远程电子传输能力，通过嵌入细胞膜中的高度有序的纤维网络产生超过厘米距离的电流。这些周质线的电导率对于生物材料而言异常高，但是其化学结构和潜在的电子传输机制仍未解决。在这里，我们结合高分辨率的显微镜，光谱学和化学成像对单个电缆细菌细丝，以证明周质线由被绝缘壳层包围的导电蛋白核组成。核心蛋白包含一个硫连接的镍辅助因子，当镍被氧化或选择性去除时，电导率会降低。镍作为活性金属参与了生物传导，这一点非常显着，