Regensburg 2025 – scientific programme

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BP: Fachverband Biologische Physik

BP 4: Bacterial Biophysics

BP 4.5: Talk

Monday, March 17, 2025, 10:45–11:00, H46

CISS Effect in Bacterial Extracellular Electron Transfer — •Nir Sukenik¹, Mohamad El Naggar¹, Yossi Paltiel², Ron Naaman³, and Lech Tomasz Baczewski⁴ — ¹University of Southern California, Lis Angeles, CA, USA — ²Hebrew University of Jerusalem, Jerusalem, Israel — ³Weizmann Institute of Technology, Rehovot, Israel — ⁴Polish Academy of Sciences, Warsaw, Poland

Electron transfer through chiral molecules is characterized by a coupling between the electron velocity and its spin through the Chirality Induced Spin Selectivity (CISS) effect. Since most biomolecules are homochiral, it was recently hypothesized that CISS underlies the highly efficient electron transfer observed in biological systems by reducing the probability of electron backscattering. A remarkable example of efficient long-distance electron transport in biology is the extracellular respiration of metal-reducing bacteria, where a pathway composed of multiheme cytochromes facilitates extracellular electron transfer (EET) from the cellular interior to external electrodes. Using conductive probe atomic force microscopy measurements of protein monolayers adsorbed onto ferromagnetic substrates, we show that electron transport is spin selective in two of the multiheme cytochromes, the membrane-associated decaheme MtrA and the tetraheme periplasmic STC. To assess the in vivo physiological impact of CISS, we also present evidence that the respiration of a different EET capable bacterium, depends on the magnetization direction of the underlying ferromagnetic electrode. Taken collectively, our results demonstrate the important role of spin in a biological mechanism essential to life.

Keywords: CISS effect; Extracellular Electron Transfer; Multiheme Cytochromes