LiveWire – Identifying the conductive molecules for long-distance electron transfer in cable bacteria

ongoing

Cable bacteria are multicellular filamentous bacteria found in surface sediments worldwide. They contain highly conductive periplasmic fibers (PCF) and use these fibers for intercellular long-distance electron transfer. The cells in the filament separate their energy metabolism, with most cells buried in anoxic sediment oxidizing sulfide, while a few cells at the surface use the resulting electrons for oxygen reduction. Cable bacteria significantly impact sediment geochemistry, affecting pH, ion mobility, sulfide release, and methane emissions. While their environmental interactions are well understood, the molecular principles for intercellular electron transport are still unclear. It is known that the conductivity of PCF exceeds that of any other biological material and that the PCF contains nickel, likely in the form of a novel nickel-sulfur cofactor but their protein composition was not identified. My research focus is to unravel the PCF composition and structure, as well as to identify proteins that mediate electron transfer to/from the PCF. I will combine four parallel experimental approaches: metalloproteomics, Cryo-EM, isotope labeling/NanoSIMS, and immunolocalization to study proteins in cell fractionations and in situ in intact cable bacteria. Identifying the highly effective nickel-based bioconductor and its interacting proteins is significant for understanding long-distance electron transfer and the division of labor in these multicellular prokaryotes. Revealing the PCF structure has potential applications for designing fiber polymers, conductive biomaterials, and biodegradable electronics. Through the interdisciplinary approach of LiveWire, I will expand my scientific expertise in biochemistry, structural biology, and cell imaging under the supervision of leading experts in these fields. In addition, I will improve my leadership, mentoring, and networking competencies to become a future independent research leader.