Methane-consuming microbial partners use redox conductors to pass electrons.

Conductive particles are abundant in coastal sediments, yet the organisms and pathways that use them for methane production remain unclear. We applied long-read, genome-resolved metagenomics to a sedi...

Methanogenic archaea, including Methanosarcina, play crucial roles in biotechnology and climate processes, impacting wastewater treatment, carbon capture, and greenhouse gas emissions. Methanosarcina ...

Methanogenic archaea generate two-thirds of Earths methane. Some reduce CO2 by drawing electrons directly from solid substrates. Yet many, including Methanosarcina barkeri, lack the multiheme cytochromes (MHCs), that drive extracellular electron transfer (EET) in other microbes. Here we show that at growth onset, M. barkeri releases an extracellular nucleic-acid pool dominated by short RNAs (~80%) that self-assemble into G-quadruplexes (G4) on the cell surface. Addition of synthetic G4-RNA doubles cathodic methane production, whereas nuclease digestion abolishes EET. Neither treatment affected growth on soluble substrates. Thus, G4-RNA forms an electron conduit enabling cathodic EET in this MHC-deficient archaeon. The discovery broadens the inventory of biological wiring and hints that nucleic-acid electronics pre-date protein redox systems, with ramifications for early-Earth metabolism, bioenergy and living electronics. ### Competing Interest Statement The authors have declared no competing interest. Novo Nordisk Foundation, https://ror.org/04txyc737, NNF21OC0067353 European Research Council, 101045149