Bacterial extracellular electron transfer components are spin selective
Abstract
Metal-reducing bacteria have adapted the ability to respire extracellular solid surfaces instead of soluble oxidants. This process requires an electron transport pathway that spans from the inner membrane, across the periplasm, through the outer membrane, and to an external surface. Multiheme cytochromes are the primary machinery for moving electrons through this pathway. Recent studies show that the chiral-induced spin selectivity (CISS) effect is observable in some of these proteins extracted from the model metal-reducing bacteria, Shewanella oneidensis MR-1. It was hypothesized that the CISS effect facilitates efficient electron transport in these proteins by coupling electron velocity to spin, thus reducing the probability of backscattering. However, these studies focused exclusively on the cell surface electron conduits, and thus, CISS has not been investigated in upstream electron transfer components such as the membrane-associated MtrA, or periplasmic proteins such as small tetraheme cytochrome (STC). By using conductive probe atomic force microscopy measurements of protein monolayers adsorbed onto ferromagnetic substrates, we show that electron transport is spin selective in both MtrA and STC. Moreover, we have determined the spin polarization of MtrA to be ∼77% and STC to be ∼35%. This disparity in spin polarizations could indicate that spin selectivity is length dependent in heme proteins, given that MtrA is approximately two times longer than STC. Most significantly, our study indicates that spin-dependent interactions affect the entire extracellular electron transport pathway.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Oct 09, 2023
- Source ID
- 10.1063/5.0154211
Entities
People
- Anne K Jones
- Christina M. Niman
- Justus Nmaduka Nwachukwu
- Kakali Santra
- Lech Baczewski
- Miyuki A. Thirumurthy
- Mohamed Y El-Naggar
- Nir Sukenik
- Ron Naaman
- Tapan Kumar Das
- Tram Dang
- Yossi Paltiel
Organizations
- Air Force Office of Scientific Research
- Arizona State University
- Fulbright Association
- Gordon and Betty Moore Foundation
- Hebrew University of Jerusalem
- Institute of Physics
- Office of Naval Research
- University of Southern California
- W. M. Keck Foundation
- Weizmann Institute of Science