The Malvankar Lab

Electronic control of bacterial behavior via natural and synthetic protein nanowires

Deep in the ocean or underground, where there is no oxygen, Geobacter “breathe” by projecting tiny protein filaments called “nanowires” into the soil, to dispose of excess electrons resulting from the conversion of nutrients to energy. These nanowires enable the bacteria to perform environmentally important functions such as cleaning up radioactive sites and generating electricity. Using cryo-electron microscopy, our lab has discovered that heme molecules line up to create a continuous path along which electrons travel with surrounding proteins acting as an insulation for these wires (Cell 2019 & Nature Chemical Biology 2020)

This discovery of nanowires was selected as Proteopedia’s  highest impact structures of the century and the New York Times commented as “a strong reminder of how ready we are to ignore things we cannot imagine.” Our work explains how bacteria use nanowires for interspecies electron transfer (Science 2010), and electricity production via biofilm communities (Nature Nano 2011). Our work thus provides new insights into bacterial survival mechanisms to control their pathophysiology and ecology and demonstrates a bottom-up approach to develop self-repairing and robust electronic materials.

Following are three major research themes of our lab:

1) Assembly machinery: We are identifying the nanowire assembly machinery using genetic tools combined with x-ray crystallography and cryo-electron microscopy and tomography.

2) Conductivity Mechanism: Existing models of biological electron transfer cannot fully explain such high conductivity in proteins. We are building a new fundamental framework by performing conductivity measurements as a function of several physical and chemical probes.

3) Synthetic Protein Nanowires: We are crystallizing conductive proteins and incorporating non-standard amino acids to develop self-assembling electronically and optical biomaterials.