Electrode-associated growth reveals structure of OmcZ-type cytochrome nanowires in anaerobic methanotrophic archaea.

Cultivation of freshwater anaerobic methanotrophic archaea on poised electrodes yields near-axenic Candidatus Methanoperedens vercellensis (95.8% relative abundance) and reveals 3.3 Å cryo-EM structures of polymerized OmcZ-type nanowires.

• Why it matters: ANME archaea regulate methane emissions in anoxic settings, but their physiology is hard to study without axenic cultures, limiting mechanistic understanding of extracellular electron transfer.
• What they did: The team grew the archaeon on poised electrodes to measure growth and electron-transport traits, then used 3.3 Å cryo-electron microscopy to resolve surface filaments containing OmcZ-type cytochrome nanowires.
• The result: The OmcZ-type nanowires show dense collinear heme stacking with post-translational modification, do not form interconnected networks, and assemble into nanowires even without the bacterial prolyl isomerase, enabling molecular models of archaeal EET.

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