Algae in the DISCO! (AI generated image before it was cringy to do that)

🚨 New Preprint! 🚨
For my PhD, I investigated an over 20-year-old mystery in photosynthesis: What does the highly conserved but enigmatic protein cytochrome c6A actually do?
We found: c6A helps algae stayin' alive in the "DISCO". 🪩

See the thread below & read the preprint: doi.org/10.64898/202...

Thanks to all the authors in Chris Howe's, @biophotoelectro.bsky.social and other labs who contributed over the years. Also to the fantastic (and super quick) editors and reviewers whose comments greatly improved the manuscript, as well as the BBSRC and others for funding. (10/10)

This technique (native membrane electrochemistry) combines the interpretability of protein electrochemistry with the complexity of microbial electrochemistry. We envision applications in investigating #bioenergetics, as well as #bioelectricity and #biocatalysis. (9/10)

We also identified how wiring membranes to electrodes has inherent advantages in #biohybrid devices for energy conversion. Here we obtain photocurrents at -600 mV vs SHE; ~1V more negative (much higher energy electrons) than is achievable with isolated proteins. (8/10)

We also showed how these electrochemical measurements can be coupled to spectroscopy, with parameters from each showing agreement with one another. (7/10)

This alone demonstrates that electrochemistry can interrogate complex biological systems, but what can we actually use it for? Here we use the Spike Charge to measure respiratory reduction and oxidation of the #quinone pool (↑Spike Charge = ↑quinone reduction). (6/10)

Through many experiments (different inhibitors, mutants, experimental conditions) we could disentangle the different electron transfer pathways within the membranes. This enabled us to create a detailed model of electron transfer between the membranes and the electrode. (5/10)

These parameters were dependent on different interfacial electron transfer pathways, shown here by the different effects of photosynthetic inhibitors. This suggested analysis of photocurrents could provide information on different membrane electron transfer pathways! (4/10)

These specialised electrodes enabled sensitive measurements of photocurrents, revealing a distinct profile (not observed in previous studies) which was quantified as two parameters: the Spike Charge and the Steady State Photocurrent. (3/10)

To analyse bioelectrical pathways, we interfaced thylakoid membranes isolated from #cyanobacteria with structured #electrodes. These #membranes contain a highly complex network of electron transfer, including electron transport chains for #photosynthesis and #respiration. (2/10)

Dissecting Bioelectrical Networks in Photosynthetic Membranes with Electrochemistry Photosynthetic membranes contain complex networks of redox proteins and molecules, which direct electrons along various energy-to-chemical interconversion reactions important for sustaining life on Ea...

Our latest paper is out now in @jacs.acspublications.org . In this study we tried to push the limits of #electrochemistry beyond proteins, to studying entire pathways of biological electron transfer ⚡️🦠. Here's a summary 🧵 (1/10)

pubs.acs.org/doi/10.1021/...

Iron reduction under oxic conditions by Microbacterium deferre sp. nov. A1-JKT - Nature Communications In this study, the authors show that Microbacterium deferre A1-JK, a newly isolated Gram-positive bacterium, simultaneously reduces oxygen and iron under oxic conditions, revealing unexpected microbia...

Out now! Simultaneous aerobic and anaerobic respiration enabled via extracellular electron transfer. Meet Microbacterium deferre A1-JK.
www.nature.com/articles/s41...

Was great to be part of this study headed up by @scaralbi.bsky.social. We are very excited by the finding that chromosomal polyploidy could be an important driver in the #evolution of #cyanobacteria and other prokaryotes. 🧬🦠

This work wouldn't have been possible without my fantastic colleagues in the Zhang lab (@biophotoelectro.bsky.social), Howe lab, and further afield. Also my funders @ukri.org, Leathersellers' foundation and Trinity Hall, who have supported this work which has bridged my PhD and fellowship. 15/15

Because cyanobacterial thylakoid membranes have some of the most complex electron transport pathways known to nature, the technique should be readily transferrable to any biological membrane. We foresee its use in characterising bioenergetic pathways and biohybrid systems. 14/15

We think natural membrane electrochemistry sits nicely between protein electrochemistry and microbial electrochemistry in terms of data complexity and interpretibility, making it a perfect system for studying biological electron transport at a systems-level. 13/15

This thread is a very high-level look at the manuscript which, like biolectrochemistry data, is very information-dense. All comments and questions are welcome! 12/15

We also developed a spectroelectrochemistry set-up, which we used to prove that these changes in the Spike Charge matched biophysical measurements of plastoquinone pool reduction. 11/15

In this graph we can see that the magnitude of the feature depends on the dark time (during which quinone reduction occurs), the addition of substrates for dehydrogenase enzymes which reduce the quinone pool, or the deletion of oxidase enzymes which oxidise the quinone pool. 10/15

But how is this useful? To demonstrate the power of this technique, we used the Spike Charge feature to provide a direct electrochemical readout of plastoquinone pool reduction. 9/15

To cut a (very long) story short, from these experiments we were able to build a model of the electron transfer processes happening within the isolated thylakoid membranes, and between them and the electrode. 8/15

In addition to testing experimental conditions and mutants, the beauty of electrochemistry is that just by changing our electrode potential we could control which cofactors could transfer electrons to the electrode; as demonstrated in stepped chronoamperometry experiments like this one. 7/15

We were were able to show how these two electrochemical parameters related to different thylakoid membrane electron transport pathways, including components of the photosynthetic and respiratory electron transport chains. Disentangling signals from these overlapping pathways is very difficult! 6/15

When recording photocurrents (change in current over a photoperiod) using these electrodes, we observed a unique profile which could be analysed using two electrochemical parameters: the Steady State Photocurrent and the Spike Charge. 5/15

Here, we use highly structured electrodes to perform sensitive electrochemical measurements of the thylakoid membranes of our favourite organisms, #cyanobacteria. These contain very complex electron transport pathways, with #photosynthesis and #respiration occuring in the same membranes. 4/15

There has been some spectacular research in recent years on interfacing membranes and cell biofilms with electrodes (check the references for some of these). But the low sensitivity and high complexity of these analytes have hindered analysis of electron transport in these complex systems. 3/15

Electrochemistry enables information-rich analysis of redox proteins and enzymes, both soluble and membrane-bound. However, its reliance on protein purification limits it to just one or a few proteins/complexes, which differs from the complexity of electron transport in living cells. 2/15

Thanks to @cenmag.bsky.social for this great article about our efforts to create music with algae 🎶🦠

Algae at the interface Explore the article collection: Algae at the interface. Published in Applied Phycology.

For more papers of this ilk, check out the special issue on 'algae at the interface', which this publication is part of. 12/12

www.tandfonline.com/journals/tap...

A big thank you to Juliet Brodie, as well as the rest of the Applied Phycology editorial team and our peer reviewers for helping us with this (rather unorthodox) paper. 11/12