From PNNL Lab: “Fluorescent Probes Increase Understanding of Bacterium’s Electron Transfer”
Electron migration via protein trafficking tightly regulated by cell
“Results: When it comes to transporting a cell’s valuable electrons, the metal-reducing microbe Shewanella oneidensis only trusts stable, mature proteins, according to scientists at Pacific Northwest National Laboratory. Immature proteins are degraded before they can take up the task, suggesting that protein trafficking to the outer membrane is tightly regulated.
These results mark another step toward understanding the cellular mechanisms that enable a bacterial protein-in this case, the cytochrome MtrC-to transfer electrons to minerals in soil, sediment, and subsurface materials. This new information contributes to understanding protein stability and electron transfer between cells and minerals, which is important for applications in synthetic biology such as biofuel production. The results were published in the journal Biochemistry.
Why it matters: Electron transfer by MtrC, an outer membrane cytochrome on S. oneidensis, can stabilize contaminants, mitigating their impact on the population and environment. However, scientists believe that gaining insight into the electron transfer mechanisms could also play a role in directing the bacterium toward biofuel production.
‘Our goal is to define the role of these cytochromes in the metabolic switching between different terminal electron acceptors,’ said Dr. Thomas Squier, a PNNL biochemist and senior author of the publication. ‘The long-term goal is to understand the stability and targeting mechanisms important to synthetic biology applications involving, for example, chemical sensing between living cells and electronic detectors as well as the development of biofuel cells.’ “

Structures of biarsenic fluorophores, CrAsH-EDT2 and FlAsH-EDT2. FlAsH-EDT2 represents a fluorescein scaffold derivatized with two As(III) groups (4′,5′-bis(1,3,2-dithioarsolan-2-yl)fluorescein). Each arsenic is capped with an ethanedithiol (EDT). Similarly, CrAsH-EDT2 represents 6-carboxy-FlAsH-EDT2.
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Pacific Northwest National Laboratory is a Department of Energy Office of Science national laboratory where interdisciplinary teams advance science and technology and deliver solutions to America’s most intractable problems in energy, the environment and national security.


