Electron transport in biological systems is classically thought to occur over nanometre to micrometre distances. Yet, recent studies on filamentous cable bacteria suggest that electrical currents can also run over centimeter distances, thus giving a whole new meaning to the term long-range biological transport. These electrical currents are channeled through protein fibers embedded in the cell envelope, which display extraordinary electrical properties for a biological material. Here we present the latest insights into the mechanism of long-range conduction in cable bacteria. Cryogenic electrical characterization reveals that the conductivity remains anomalously high at extremely low temperatures. This conductivity behavior has not been seen before in a biological structure and challenges our understanding of protein biophysics. New data reveal that the conductive protein fibers in cable bacteria contains a planar nickel cofactor, which is stacked to form a linear metal organic framework. This metal organic framework forms an efficient and flexible one-dimensional conduit for long-distance electron transport. This observation is highly remarkable from a biochemical point of view, as all known metalloproteins involved in biological electron transport rely on Fe or Cu cofactors, but never Ni-centers. Together, these recent data suggest that the conduction mechanism in cable bacteria is different from known biological electron transport mechanisms. Our findings reveal a novel biological structure with an unprecedented conductivity that could form the basis of new bio-electronic applications and radically new green technologies.