Reardon, Patrick N. and Karl T. Mueller. (2013) Structure of the Type IVa Major Pilin from the Electrically Conductive Bacterial Nanowires of Geobacter sulfurreducens. J. Biol. Chem. 288: 29260-29266 doi: 10.1074/jbc.M113.498527.
Structure of the Type IVa Major Pilin from the Electrically Conductive Bacterial Nanowires of Geobacter sulfurreducens
Some bacteria possess the incredible ability to produce and conduct electricity. This electricity is actually a waste product of their metabolism under certain conditions and is a research focus in the field of bioenergy. A number of these bacteria contain long filaments that protrude from their body called pili (plural of pillus). Without these pili, electrical conductance is drastically reduced. A major mystery is how bacteria are able to conduct electricity over relatively long distances using a long protein structure. Researchers in this study determined the actual protein structure of pilin A, the major protein that connects together like legos to produce the pili. Using a pilus model based upon observation in another bacterium, scientists fit this new structure and determined a proposed mechanism of how electrical charge is conducted. This proposal states that electrons produced as waste within the cell are shuttled out then ‘hop’ across pili via aromatic amino acids (ring-structured R group) positioned along the length of the pilus to some electron acceptor. This new knowledge can help scientists make more efficient microbial fuel cells as a viable alternative fuel source.