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Abstract Extracellular electron transfer (EET) via microbial nanowires drives globally-important environmental processes and biotechnological applications for bioenergy, bioremediation, and bioelectronics. Due to highly-redundant and complex EET pathways, it is unclear how microbes wire electrons rapidly (>106 s−1) from the inner-membrane through outer-surface nanowires directly to an external environment despite a crowded periplasm and slow (<105 s−1) electron diffusion among periplasmic cytochromes. Here, we show thatGeobacter sulfurreducensperiplasmic cytochromes PpcABCDE inject electrons directly into OmcS nanowires by binding transiently with differing efficiencies, with the least-abundant cytochrome (PpcC) showing the highest efficiency. Remarkably, this defined nanowire-charging pathway is evolutionarily conserved in phylogenetically-diverse bacteria capable of EET. OmcS heme reduction potentials are within 200 mV of each other, with a midpoint 82 mV-higher than reported previously. This could explain efficient EET over micrometres at ultrafast (<200 fs) rates with negligible energy loss. Engineering this minimal nanowire-charging pathway may yield microbial chassis with improved performance.
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This content will become publicly available on January 15, 2026
A widespread and ancient bacterial machinery assembles cytochrome OmcS nanowires essential for extracellular electron transfer
Microbial extracellular electron transfer (EET) drives various globally-important environmental phenomena and has biotechnology applications. Diverse prokaryotes have been proposed to perform EET via surface-displayed “nanowires” composed of multi-heme cytochromes. However, the mechanism that enables only a few cytochromes to polymerize into nanowires is unclear. Here, we identify a highly-conserved omcS-companion (osc) cluster that drives the formation of OmcS cytochrome nanowires in Geobacter sulfurreducens. Through a combination of genetic, biochemical, and biophysical methods, we establish that prolyl isomerase-containing chaperon OscH, channel-like OscEFG, and β-propeller-like OscD are involved in the folding, secretion, and morphology maintenance of OmcS nanowires, respectively. OscH and OscG can interact with OmcS. Furthermore, overexpression of oscG accelerates EET by overproducing nanowires in an ATP-dependent manner. Heme loading splits OscD and ΔoscD accelerates cell growth with bundling nanowires. Our findings establish the mechanism and prevalence of a specialized and modular assembly system for nanowires across phylogenetically-diverse species and environments
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- Award ID(s):
- 2210473
- PAR ID:
- 10563568
- Publisher / Repository:
- Cell Chemical Biology
- Date Published:
- Journal Name:
- Cell chemical biology
- ISSN:
- 2451-9456
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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