Scientists Show How Bacteria Move Electrons Across a Membrane

PhysOrg.com
December 29, 2009

PhysOrg.com) -- Scientists at the University of East Anglia, Pacific Northwest National Laboratory, and Pennsylvania State University have demonstrated for the first time the mechanism by which some bacteria can transfer electrons across a membrane to the cell exterior, allowing them to "breathe" metals. These iron-respiring bacteria link the cycling of iron and carbon in subsurface and surface sediments and can catalyze the immobilization of subsurface contaminants such as uranium.

In an article published in Proceedings of the National Academy of Sciences, the researchers described the protein complex -- and its electrochemical properties -- from Shewanella oneidensis, a bacterium renowned for its diverse metabolism and ability to immobilize certain radioactive contaminants. This research demonstrated a novel outer membrane-spanning electron transfer system that enables the proteins MtrA (inward facing) and MtrC (outward facing) to embed sufficiently within a third transmembrane protein, MtrB, to allow electron transfer to take place between them.

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