Brandán Pedre

Thanks a lot!

Only reduced cysteine, and there is no disulfide exchange mechanism needed for its detection (it is based on non-covalent binding-dependent conformational modifications).

If you work on:
#redoxbiology #metabolism #ferroptosis #mitochondria #biosensors

…and want to monitor cysteine dynamics in your system, Cystector might help (🧬 Plasmids soon available on Addgene!).

Happy to discuss applications or adaptations-DMs welcome!

Across systems, Cystector enables:
• live-cell measurements
• subcellular resolution
• cross-domain comparisons
• minimal perturbation of metabolism

We also targeted Cystector to the mitochondrial matrix.

🔍 Result:
• mammalian mitochondria maintain higher cysteine levels than the cytosol
• under cysteine-limiting conditions, mitochondrial cysteine recovery is prioritized

Mitochondrial and cytosolic cysteine pools are not equivalent.

In mammalian cells, Cystector reports:
• cysteine depletion upon H₂O₂ treatment
• rapid cysteine loss following erastin2 or glutamate (therefore dynamics relevant to ferroptosis)

In yeast, Cystector shows that cysteine homeostasis:
• depends strongly on energy (fermentation vs. respiration) state
• is reshaped under oxidative stress

In E. coli, Cystector reveals that:
• imported cystine is rapidly reduced to cysteine
• excess cysteine is exported into the extracellular medium
• glutathione and glutaredoxins are key for cystine reduction

Cystector enabled the direct visualization of a long-standing hypothesis.

We then asked: what can we learn if we use the same cysteine sensor across organisms?

We applied Cystector in:
Escherichia coli
Saccharomyces cerevisiae
Mammalian cells

💡 Cystector is a genetically encoded, ratiometric fluorescent biosensor that directly reports cysteine binding.

Key properties:
• very large dynamic range (~4500%)
• minimal sensitivity to physiological pH
• high selectivity for cysteine over thiol-containing molecules, including glutathione

Existing approaches struggle because cysteine:
• oxidizes during cell lysis
• is modified by chemical probes that measure it
• is confounded by high glutathione levels

➡️ We needed a non-invasive, selective, live-cell tool.

Why cysteine?
Cysteine is central to:
• thiol redox regulation
• glutathione & CoA synthesis
• iron-sulfur cluster assembly
• ferroptosis

Yet, tracking dynamic cysteine levels in living cells has been extremely challenging.

🧪🧬 New preprint!
What if the same biosensor could reveal how cysteine is regulated across life domains?

We introduce Cystector, a genetically encoded fluorescent biosensor for real-time cysteine monitoring in living cells.

www.biorxiv.org/content/10.6...

🧵A thread ⬇️

Combining FRET and super-resolution microscopy reveals kinase activation and mitochondrial activity at the nanoscale Protein kinases are key regulators of intracellular signaling, showing activities in specific subcellular compartments and in micro- or nano-domains. Genetically encoded biosensors based on Förster′s ...

Excited to share our #BioSenSRRF preprint on bioRxiv! 🎉
We show how SRRF microscopy can be used with FRET-based biosensors to 🔬mitochondrial functions with high resolution 😍.
Code and test data are open (GitHub + Zenodo).
👏 to Nicolas, Pierre-Jean, and co-authors! www.biorxiv.org/content/10.1...

Just wrapped up a fantastic week at the EMBO Workshop on Thiol-Based Redox Switches. Great science, great discussions, and a truly inspiring community. Huge thanks to the organizers @danareichmann.bsky.social and Tobias Dansen for their hard work in putting together such a memorable meeting!

Thiol-based redox switches: From chemistry to physiology and pathology Redox reactions have been essential for the emergence of life on Earth, and diverse strategies have evolved for responding to various cellular redox species. These mechanisms are still of vital impor…

The @EMBO workshop #EMBOthiolSwitches is coming up soon, join us in beautiful Sant Feliu de Guíxols, Spain, 13–18 September 2025!
We have a fantastic speaker lineup, with a few spots still open for short talks. Abstract deadline extended to 31 May 2025.

meetings.embo.org/event/25-thi...

The Barrier Properties of Biological Membranes Dictate How Cells Experience Oxidative Stress Molecular oxygen diffuses across membranes with such speed that, despite respiration, the intracellular oxygen concentration does not differ significantly from that outside the cell. In contrast, mem...

James Imlay turns redox chaos into clockwork: his new paper shows how membrane permeability sets the tempo of oxidative stress, with straight-up back-of-the-envelope math in the appendix. Fundamental, elegant, causal.
onlinelibrary.wiley.com/doi/10.1111/...

🧵 1/6
Just dropped in @naturecomms.bsky.social

We’ve engineered the most photostable yellow fluorescent proteins (YFPs) to date—mGold2s and mGold2t—with up to 25× greater photostability than mVenus and mCitrine, without compromising brightness.

👇
🔗 www.nature.com/articles/s41...

A palette of bright and photostable monomeric fluorescent proteins for bacterial time-lapse imaging Bright and photostable monomeric fluorescent proteins enable long-term time-lapse imaging in E. coli.

A palette of bright and photostable monomeric fluorescent proteins for bacterial time-lapse imaging | Science Advances www.science.org/doi/10.1126/...

Exclusive: the most-cited papers of the twenty-first century A Nature analysis reveals the 25 highest-cited papers published this century and explores why they are breaking records.

The most-cited papers of the twenty-first century

...and the reflection of the capricious citation culture:
🤖
www.nature.com/articles/d41...

On the responsibilities of intellectuals and the rise of bullshit jobs in universities You may never have considered yourself to be one. Why would you? But if you’re reading this, there is more than a likelihood that you are one. If you’re a

touché.

academic.oup.com/brain/articl...

A long but fruitful journey: from a roGFP2-based drug screen to reaching protein targets of the proton pump inhibitor rabeprazole. Congratulations to all the authors! @aubrykmiller.bsky.social

Dual-expression system for blue fluorescent protein optimization - Scientific Reports Scientific Reports - Dual-expression system for blue fluorescent protein optimization

We are very excited to see the first orange flame lit up for our plasmid pHybrid-Electra2 on Addgene, which is designed for gene expression in E. coli and mammalian cells www.nature.com/articles/s41...

First Bluesky post! 👋 I work designing fluorescent indicators for redox biology. Last year, I published a review on genetically-encoded redox biosensors—DM me if you’d like a copy! Happy to connect with fluorescence enthusiasts and redox biologists. #FluorescenceFriday

doi.org/10.1016/j.ab...

Postdoctoral position in the group of Dr. Antonio Martínez Ruiz in Madrid

Do you want to work as a #postdoc in our group in a Hospital Research Institute in Madrid?🏥🔬

Interested in how #mitochondria and #redox signalling/stress can influence #stroke outcome and #inflammation?🧠💊

Apply up to 26 December at n9.cl/iunkw (ref 72/2024)
Full call n9.cl/gijjd

Please repost 😉

Thank you very much for your initiative @tonnomartinez.bsky.social !