A bundled anti-parallel cytochrome nanowire structure suggests roles in cell-cell electron transfer and biofilm formation.

Cryo-electron microscopy reveals that a unique cytochrome nanowire from Desulfuromonas soudanensis forms highly ordered, conductive bundles of anti-parallel filaments, suggesting a common nanowire structure.

• Why it matters: Understanding the higher-order structure of extracellular electron transfer nanowires is crucial because it may explain how microbes form conductive biofilms and facilitate cell-cell electron exchange, yet this remains largely unknown.
• What they did: The study used cryo-electron microscopy to determine the atomic structure of OmcE-based nanowire bundles from D. soudanensis and observed similar structures in Geobacter metallireducens, indicating widespread nanowire bundling.
• The result: These bundles are conductive with conductance increasing in a concentration-dependent manner and exhibit redox activity over a ~370 mV window, implying they could enable stable biofilm formation and direct microbial electron transfer.