Imaging Charge Flow along Bacterial Proteins Reveals a Novel Mechanism of Biological Electron Transport
| Date/Time: | Thursday, 22 Jan 2015 from 4:10 pm to 5:00 pm |
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| Location: | Physics 0003 |
| Phone: | 515-294-5441 |
| Channel: | College of Liberal Arts and Sciences |
| Actions: | Download iCal/vCal | Email Reminder |
Abstract: Living cells are required to get rid of a large number of electrons left behind in metabolism when nutrients convert into energy. Aerobic organisms inhale oxygen to dump these excess electrons. However, some harsh environments don't afford the luxury of soluble, ingestible electron acceptors. Cells devise unique strategies using membrane proteins to export electrons outside their body, but the exact mechanism remains unclear. Electron transport in proteins generally occurs via tunneling or hopping mechanism and the possibility of electron delocalization or metal-like conductivity has been considered previously impossible. I will present our recent measurements on protein nanofilaments, pili, of a common soil microorganism Geobacter sulfurreducens that challenge this long-standing belief. Using a novel scanning probe microscopy-based approach to visualize charge propagation in native biomolecules, we have found out that pili propagate charges in a delocalized manner similar to metallic carbon nanotubes, enabling cells to carry out respiration and cell-to-cell electron exchange over several micrometers. Structural and molecular studies revealed that conductive pili possess unique arrangement of aromatic amino acids that facilitate intermolecular electron delocalization. My studies suggest that the ability to directly image and measure electrical charges in cells and their components, under physiologically relevant conditions, can result in a new approach to probe cellular interactions in environmentally as well as clinically important systems.
Bio: Nikhil received M.S. in Physics from Indian Institute of Technology, Bombay and PhD in Physics from the University of Massachusetts, Amherst under Prof. Mark Tuominen. His graduate studies at the cellular level revealed that living cells show high electronic conductivity as well as large electron storage capacity due to extracellular proteins. His post-doctoral studies at the molecular level with Prof. Derek Lovley in the Microbiology department identified the protein architecture responsible for the conductivity. Nikhil has recently received a Career Award at the Scientific Interface (CASI) by Burroughs Wellcome Fund. He is interested in understanding how electrical charges in living cells drive complex biological processes and cause severe bacterial infections.