Dissecting a biological electron transport network with electrochemistry

Electron transport chains (ETCs) drive fundamental biological processes, including respiration and photosynthesis. Methodology for studying biological electron transport on a systems-level is lacking, owing to ETCs forming complex overlapping networks of electron transfer, akin to cellular metabolism. Here, we demonstrate the use of electrochemistry to study the highly complex electron transport found in the thylakoid membranes of cyanobacteria. By interfacing thylakoid membranes with highly structured electrodes, we revealed electrochemical signatures originating from the direct electron transfer (DET) between membrane components and the electrode. Analysis of these signatures enabled the measurement and disentanglement of respiratory and photosynthetic signals, with results exhibiting consistency with biophysical measurements of ETC activity. These findings establish natural membrane electrochemistry as a useful tool for investigating biological electron transport from the scale of individual proteins to entire ETCs, with immediate applications in analysing membrane bioenergetics and guiding the design of biohybrid energy-conversion technologies.