Understanding the Roles Played by Hydrosulphide Membrane Channel and Its Relatives in Living Systems


The hydrosulphide ion (HS–), a critical element in the origin of life on Earth, is important in physiology and cellular signaling. The HS–species is also the terminal product when an anaerobic bacterium derives its oxidative power from sulphate instead of oxygen. A recent study conducted on beamlines at the National Synchrotron Light Source revealed the structure of the hydrosulphide ion channel (HSC), a membrane-pore molecule, elucidating how HS– is able to escape from pathogenic Clostridium difficile cells. In the same protein family, the formate channel (FocA), which has a fold similar to HSC, has been shown to play two other roles related to bioenergy and environmental science. In the first case, hydrogen gas production in Escherichia coli depends on the selective decomposition of formate, whose concentration depends on FocA. In the second, when Euglena experiences long-term chronic exposure to cadmium ions, it overexpresses a FocA protein. This protein has been proposed as a marker for long-lasting cadmium pollution in water.


Czyzewski, B. K., and D.-N. Wang. 2012. “Identification and Characterization of a Bacterial Hydrosulphide Ion Channel,” Nature 483, 494–97. (Reference link)