Anuj

Cryo-EM structure of Chlamydomonas Photosystem I complexedwith the alternative electron donor cytochrome c6 www.biorxiv.org/content/10.1101/2025.09.08.674899v1 #cryoEM

Initial attempt at replicating in relion (parameters in next post). This is for Aca2-RNA, using a 100k subset of the 2D-classified particles (no prior 3D cleanup).

A 1-class ab initio in relion, then local refinement in relion (1.8deg searches+blush) gives a nominally 3.3Å map; 3.5 Å w/out blush.

Happy to share that our story on the bacterial archaellum was published today in @natmicrobiol.nature.com
www.nature.com/articles/s41...

Congrats to the authors: @sshamphavi.bsky.social @loumollat.bsky.social @mariejoest.bsky.social Najwa Taib and @sgribaldo.bsky.social

This one is a bit of a departure from the usual and definitely a work in progress!

We found that by using ab initio reconstruction at very high res, in very small steps, we could crack some small structures that had eluded us - e.g. 39kDa iPKAc (EMPIAR-10252), below.

Read on for details... 1/x

Sub-cellular chemical mapping in bacteria using correlated cryogenic electron and mass spectrometry imaging

Congrats Hannah Ochner and authors on this important paper! Strong collaboration with @kiranrpatil.bsky.social

www.biorxiv.org/cgi/content/...
@mrclmb.bsky.social @wellcometrust.bsky.social

It is out now 🥳🥂
I am very happy to be part of this nice collaboration in which we were able to characterize different bacterial chemoreceptors and their ligand specificities. Amazing teamwork with Wenhao Xu, the Sourjik lab, @bangebalcony.bsky.social, et. al 🤩

👇👇👇
www.pnas.org/doi/10.1073/...

The Role of Selenocysteine in Catalysis and Oxygen Tolerance of a W-Dependent Formate Dehydrogenase Metal-dependent formate dehydrogenases (FDHs) catalyze, under mild conditions, the reversible reduction of CO2 to formate, a versatile C1 feedstock that can contribute to a carbon-neutral economy. Metal-dependent FDHs are the most widespread selenoproteins found in bacteria, and around 44% of them include selenocysteine (Sec) as a ligand to the Mo/W active site. In the sulfate-reducer Nitratidesulfovibrio vulgaris Hildenborough, the main FDH responsible for CO2 reduction is the W/Sec-dependent FdhAB, which is among the most active CO2 reductases reported so far. In contrast to most metal-dependent FDHs, this enzyme is relatively O2-tolerant and can be purified aerobically. In this work, we evaluated the role of Sec in the catalytic and stability properties of the W/Sec-FdhAB. For that, a Sec-to-Cys variant (U192C) was created, its catalytic and spectroscopic properties were characterized, and its crystal structure was determined. Sec substitution by Cys strongly affects activity, decreases the KM for formate, and increases susceptibility to O2. While Sec-to-Cys replacement induces only weak changes of the WV EPR signals, using 77Se-labeled enzyme, we could show that Sec undoubtedly coordinates the W metal in the WV redox state. The crystal structure of U192C confirmed previous findings on the redox switch mechanism of activation and protection of FdhAB, while revealing a putative catalytic intermediate of FdhAB with Arg441 orienting a CO2 substrate analog (probably SO2) in the active site. Overall, the results indicate that Sec plays a critical role in the high activity displayed by W/Sec-FdhAB, and that it may also be involved in or modulate the proton transfer to and from the active site.

Very excited about this story: Inês Pereira et al. reveal the role of selenocysteine in catalysis and O2-tolerance of a tungsten-dependent formate dehydrogenase (via ACS Catalysis)
doi.org/10.1021/acsc...

Proud to see our work on metalloenzymes - and methyl coenzyme M reductase (MCR) in particular - featured in the print version of Berlin's @tagesspiegel.de 🤩
⛓️ www.uni-potsdam.de/fileadmin/pr...

Atomic-resolution structure of a chimeric Powassan tick-borne flavivirus The 2.8-Å resolution structure is presented for a chimeric construct of an emerging tick-borne flavivirus, Powassan virus.

New in @science.org
We built a safe, atomic-resolution version of the Powassan virus—a deadly tick-borne #flavivirus with no vaccine.
✅ First structure ever
✅ Safe to handle (BSL-2)
✅ Platform for vaccines & antivirals

Let me show you 🧵 (1/5)

Link: www.science.org/doi/10.1126/...

Our new preprint: how photoprotection is spatially coordinated with energy metabolism. Photosystem I is major source of radicals. We report EM structure of PSI in complex with superoxide dismutase SOD: direct link between energy conversion & oxidative stress defence
www.biorxiv.org/content/10.1...

Our new consensus statement on reducing and reporting contamination in microbiome studies is the cover image of this month's Nature Microbiology: www.nature.com/articles/s41... In the cover photo, you can see our postdoc Sophie Holland in fully PPE sampling the atmosphere of terrestrial Antarctica.

Electron flow in hydrogenotrophic methanogens under nickel limitation - Nature Two distantly related methanogens shift the methanogenic pathway under nickel limitation, suggesting that methanogens adapt to changing bioavailability of nickel by rerouting electron flow between two...

Our new study shows how nickel limitation changes electron flow in methanogens.
@nature.com
#methanogens #methane #archaea
www.nature.com/articles/s41...

Happy to share Yiting's new paper on artificial micro hydrogenase aka... Ferredoxin⁉️
Out now in Advanced Science doi.org/10.1002/advs...

Our ferredoxin story @chemicalscience.rsc.org now in print, just in time for my presentation tomorrow #ISABC17 👏🏻
Sahin et al., Chem. Sci., 2025, 16, 10465-10475
pubs.rsc.org/en/content/a...

Excellent work from my dear friend Sriram! Many congratulations @georghochberg.bsky.social !

Excellent work from my colleagues Tristan and Eva on the structure of the ancient sodium pumping Mtr complex from methanogens! Happy to contribute alongside @tomaspascoa.bsky.social @ezimmer.bsky.social @schullerjm.bsky.social

Clustering for methane - Nature Catalysis Nature Catalysis - Clustering for methane

CLUSTERING FOR METHANE
Nice write-up @natcatal.nature.com of our recent article on MCR activation 🙏🏻
www.nature.com/articles/s41...

Two Key Ferredoxins for Nitrogen Fixation Have Different Specificities and Biophysical Properties Two ferredoxins, FdC and FdN, are collectively essential for the process of nitrogen fixation by the iron nitrogenase in R. capsulatus. We explore the biophysical factors, through spectroscopic and s....

Leveraging spectroscopic and structural approaches we obtained new insights into the role of #ferredoxins in N2 fixation. Just published in Chemistry – A European Journal: doi.org/10.1002/chem...! Great work by Holly Addison. Fantastic collaboration with Antonio Pierik on the EPR characterization.

Interesting thread 🧵 from @georghochberg.bsky.social dissecting the evolution of nitrogenases from cofactors of methane-producing enzymes. The “molecular paleontology” possible with modern technology is so cool. 🧪🧶🧬

Happy to present the lab latest work, today from the green-side. The ultimate PSII assembly intermediate that directly precedes incorporation of the Mn4O5Ca cluster and formation of the OEC. Psb32 binds to PsbV, challenging the assumption the extrinsic subunits all associate spontaneously in-vivo.

Durchbruch in der Methan-Forschung: Aktivierungsmechanismus des Methan-produzierenden Enzyms entschlüsselt „Nature“-Publikation offenbart die evolutionäre Verbindung zwischen zwei fundamentalen biologischen Prozessen

🧪 Durchbruch in der biochemischen Grundlagenforschung mit zentraler Bedeutung für #Energie & #Klima:
Ein Team der @unimarburg.bsky.social & der #TUBerlin/ @unisyscat.bsky.social hat erstmals den Aktivierungsmechanismus des Enzyms MCR aufgeklärt – zentral für die biologische Produktion von #Methan. 👇

Figure 4. MemBrain v2 end-to-end workflow detects periodic phycobilisome organization. A: Raw tomogram slice of EMD-31244. B: Out-of-the-box MemBrain-seg segmentation (light blue). C: A single membrane instance can be visualized in Surforama and manually annotated with GT phycobilisome positions (magenta). D: MemBrain-pick localizes particles (trained with data from C) on all membranes in the tomogram. E: MemBrain-stats computes Ripley’s O statistic using the positions from D with a bin size of 5nm. The distance between peaks (35 nm) was measured to estimate chain unit spacings.

We have updated our #MemBrain v2 preprint with a lot more details about the MemBrain-pick and MemBrain-stats modules, as well as some application examples!

Stay tuned for the upcoming thread by lead author @lorenzlamm.bsky.social! 🧠🧵

#CryoET #TeamTomo
www.biorxiv.org/content/10.1...

Do you want to join the team? I just got awarded a 2 year fully funded Postdoc position to investigate the metabolism of anaerobic pathogenic bacteria. If you have a strong background in protein biochemistry or anaerobes shown by solid publications, reach out. Job add follows, please repost.

Durchbruch in der Methan-Forschung: Aktivierungsmechanismus des Methan-produzierenden Enzyms entschlüsselt „Nature“-Publikation offenbart die evolutionäre Verbindung zwischen zwei fundamentalen biologischen Prozessen

Here's what my former employer @tuberlin.bsky.social wrote about our work (🇩🇪)
www.tu.berlin/news/pressem...

@tuberlin.bsky.social chat about recent work!

Unser Heisenberg-finanzierter Arbeitsgruppenleiter Dr. Sven Stripp (links hinten) hat in Zusammenarbeit mit Kolleg*innen der @unimarburg.bsky.social einen Artikel in @nature.com publiziert. Die @unipotsdam.bsky.social berichtet:
www.uni-potsdam.de/de/nachricht...

I also count myself lucky! Its a pleasure to work together with such fascinating molecular machines and at the interface of bioenergetics and evolution!

This is a wild paper. The anaerobic biochemistry is definitely worth your while (and beyond me to explain), but let me try to explain why this is also an evolutionary bombshell. This is about how nitrogen fixation evolved as we know it.

Check this awesome work 👇🤓🥳

@fidelormz.bsky.social, I am very proud of you🤓🥳. You deserve this and more 🥰🤩

Congratulations to all the great scientists involved in this work 🥳🤩

Thank you! 🤩