Spatiotemporal organization of membrane protein controls bacterial extracellular electron transfer.

Abstract

Extracellular electron transfer (EET) is essential for electroactive microbes' physiology and biotechnological applications. Many such microbes are Gram-negative bacteria, in which EET must cross two membranes and the periplasm, necessitating spatial and temporal collaborations of various EET proteins that reside at different cellular compartments, for which little is known. Using single-molecule/single-cell-level fluorescence microscopy and electrochemical manipulations, we discover that in the electroactive bacterium Shewanella oneidensis, the inner-membrane electron-transfer hub protein CymA undergoes spatial reorganization into localized regions during active EET with dispersed formation dynamics, subsequently driving the colocalization of its direct electron-transfer partners in the periplasm. Correlated single-cell-level photoelectrochemistry-fluorescence microscopy further proves the critical function of CymA reorganization in enabling EET. A multitude of evidence suggests that CymA reorganization stems from biomolecular condensate formation, likely initiated by association with menaquinone-rich inner-membrane domains. These orchestrated spatiotemporal protein dynamics extend the functional roles of biomolecular condensates to include facilitation of EET in bacteria, with broader implications for cellular processes.