Happy to share that our work on the FDX2-bound core ISC complex is now published in @NatureComms 🎉. By the way, we are now also on @bluesky! 🦋

Our elemental mapping work, combining cryo-EM and EELS to REEL analysis, is now also published on Nature Methods:. For a highlight “reel”, see here 👇.

Congrats to @MaxYin_211013 and co-authors! Big thanks to X-ray team: Tristan Wagner, Olivier Lemaire and Mélissa Belhamri @MarineMicrobio; computational team: Gerhard Hummer and José Guadalupe Rosas Jiménez @HummerLab; MS team: Anna Shevchenko @mpicbg for the great collaboration!.

The story doesn’t end there. QM/MM calculations reveal novel features of the catalytic metalloclusters, the C-cluster and A-cluster. The results suggest an electron storage mechanism for the C-cluster, and the configuration of the A-cluster in the ligand-free resting stage.

Combining newly discovered and known states, we propose a conformation-based model of acetyl-CoA synthesis, showing how each step is facilitated by specific conformations. A 2D clustering scheme of resolved states and structural homologs strongly suggests a conserved mechanism.

The CO and methyl derived from CO₂ join with CoA to form acetyl-CoA near the A-cluster of ACS. This product-bound state is captured by X-ray crystallography. Due to oxygen sensitivity, we prepared all cryoEM grids and crystallization samples under anaerobic conditions.

How do we get there? Our cryoEM team captures missing states of CODH/ACS at sub-3Å resolution. Ferredoxin docks at CODH symmetry axis to pass electrons for CO₂ reduction into CO. ACS extends to accommodate CoFeSP, which transfers a methyl group reduced from another CO₂ molecule.

How could CO₂ fixation occur in anaerobic and ancient life? Our new preprint sheds light on catalytic mechanism of the key enzyme CODH/ACS in the Wood-Ljungdahl pathway. Watch the summary movie to see how CO₂ is transformed into acetyl-CoA. Read more:

Happy to see our study on the structure of 46-kDa Streptococcus pneumoniae NOX out in @NatureSMB! Congratulations to the authors @PABLOSANSEGUND3 and @vicsnorr 🥳.Check it out here (open-access) 👉

Many thanks to our colleagues @MPIbp and collaborators in the group of Roland Lill @Uni_MR for cooperation on this story and a study of the sulfur transfer intermediates in the frataxin-bound core ISC complex: 🧵 8/8.

Our study clarifies how FDX2 binds to the core ISC complex and confirms that de novo FeS biosynthesis is a highly concerted process. This might have implications for understanding the concentration-dependent effects of frataxin in diseases like Friedreich’s ataxia. 🧵 7/8.

Another question was whether FDX2 and the allosteric activator frataxin bind competitively or simultaneously to the complex. By fast vitrification of samples under active FeS biosynthesis conditions we could show that the proteins compete for overlapping binding sites. 🧵 6/8.

In the proximal conformation we observed that the intrinsically disordered C terminus of FDX2 becomes rigid and interacts with the ISC complex. Thus, a likely role of this isoform-specific element is to mediate the transition to an electron-transfer competent complex. 🧵 5/8

Our structures show that FDX2 can bind in two conformations, ‘distal’ and ‘proximal’ from the ISCU2 FeS assembly site. Only in the proximal conformation FDX2 binds tightly to the complex and is close enough for rapid electron transfer to the FeS assembly site. 🧵 4/8

The process requires electrons donated by the electron carrier protein FDX2, but its precise interaction with the complex has been unclear. Harnessing our anaerobic cryo-EM sample preparation setup, we made samples with reduced FDX2 using the FDX2 reductase and NADPH. 🧵 3/8.

#Mitochondria are known as the ‘powerhouses’ of the cell. But an even more widely conserved function is the biosynthesis of inorganic protein cofactors called iron-sulfur #FeS clusters, which are built de novo from free cysteine and iron by the core ISC complex. 🧵 2/8.

🎉 Our latest preprint is now online 👉 Congrats to @RalfSteinhilper who determined #cryoEM structures of the ferredoxin 2-bound core iron-sulfur cluster assembly complex under reducing and turnover conditions at 2 Å resolution. More below! 👇. 🧵 1/8

More research will be needed to reach single-atom sensitivity. In the meantime, we’d be grateful for any feedback and hope you enjoy the read!.Also, if you’d like to join the team: We do have an open post-doc position! ^^ 🧵 6/6.

A big thanks for their contributions, especially to @_Higor_Rosa, as well as Dietmar Riedel, @YuSebyChen, @FilipPetegem, and the always-helpful team from CEOS whose awesome CEFID we have been relying on, as well as @DECTRIS_News whose ELA has been crucial to this project. 🧵 5/6.

Our proof of principle data show that we can correctly localise abundant elements and perform EELS background subtraction on our reconstructed data. 🎉.🧵 4/6