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Lorenz Grundmann

@lgrundmann.bsky.social
141 followers 184 following 29 posts

PhD student in the Haselbach lab (IMP, Vienna). Visualizing proteins and cells by shooting charged particles at them.

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Reposted by Lorenz Grundmann
Max Perutz Labs Vienna @maxperutzlabs.ac.at · 26/06/2026
🆕 publication! How do cells build their molecular machines? Tsimafei Navalayeu (Ameres lab) in @embojournal.org maps the stepwise assembly of the RNA exosome in mammalian cells, revealing the quality control mechanisms that ensure this essential complex is built correctly ➡️ tinyurl.com/84c2298e
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Laurence Pearl 🔥 @laurencepearl.bsky.social · 06/06/2026
Not wanting to be snarky but this is true of every technological advance in science. My entire PhD in 1983 was the fitting and refinement of a single protein crystal structure. Today I could do the same within an hour - no AI required. Hyperbole does not help.
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joe dobbs @joedobbs.bsky.social · 03/06/2026
Super cool cryo-ET work from my colleague Xiaohan resolving a ton of ribosome assembly intermediates in the nuclei of human cells!
Figure 4 from the preprint
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Structura Biotechnology @structurabio.bsky.social · 02/06/2026
For years, the #cryoEM community viewed ~50 kDa as the practical lower size limit for SPA. This was challenged by Kim et al., who introduced the HR-HAIR method and demonstrated structure determination of proteins below 30 kDa using #CryoSPARC. Read more 👉 bit.ly/3RHMxAt
bit.ly
CryoSPARC | The Resolution Revolution Is Still Ongoing
High-Resolution Ab-Initio Reconstruction: Extending Cryo-EM to Smaller Particles with CryoSPARC™
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RCSB Protein Data Bank @rcsbpdb.bsky.social · 16/05/2026
Try this new online training game from Leandro F. Estrozi designed for newcomers in structural biology, with a focus on cryo-EM and cryo-ET map interpretation: rico.ibs.fr/helixplo...
Screenshot of online game
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Dimitry Tegunov @dtegunov.bsky.social · 03/05/2026
We're super excited to share MissAlignment: a new ML-based approach to reference-free tilt series alignment, spearheaded by @martenchaillet.bsky.social. We think it's going to make your cryo-ET life a lot better. Preprint: www.biorxiv.org/content/10.6... Code: github.com/warpem/miss-... 🧶 Thread:
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IMP @impvienna.bsky.social · 23/04/2026
Cells have a built-in cleanup system to remove unwanted proteins, and scientists can hijack it to destroy cancer drivers. Now, researchers from our Haselbach lab and collaborators reveal how this works in near-atomic detail: www.nature.com/articles/s41467-026-…
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Ahmad Jomaa @jomaalab.bsky.social · 27/03/2026
Check out the final version of this work, out today! @natcomms.nature.com www.nature.com/articles/s41...
nature.com
A molecular switch in NAC prevents mitochondrial protein mistargeting by SRP - Nature Communications
How ribosome-bound NAC distinguishes mitochondrial precursors from ER clients has remained unclear. Here, authors reveal a molecular switch in NAC that limits SRP access to nascent mitochondrial precu...
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Kashish Singh @kashishsingh.bsky.social · 24/03/2026
Happy to share my first adventure in #TeamTomo in collaboration with the talented @inaharasimov.bsky.social. It was a fun experience experience with a lot of learning along the way.
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Carter Lab @carter-lab.bsky.social · 24/03/2026
Excited to share our work on the structure and function of cytoplasmic lattices within mouse embryos. A collaborative effort with @niakanlab.bsky.social and work led by @kashishsingh.bsky.social and @inaharasimov.bsky.social . It is now out on BioRxiv: www.biorxiv.org/content/10.6...
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Leo Kiss @leokiss.bsky.social · 05/03/2026
I am incredibly excited to share that I will start my independent lab at the @unidue-zmb.bsky.social at the @unidue.bsky.social as Junior Professor of Cellular Biochemistry. Research in my lab has the goal to decipher the ubiquitin code! There are multiple open positions! (1/3)
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Florent Waltz @florentwaltz.bsky.social · 10/02/2026
Long in the making, but happy to present the Chlamydomonas chlororibosome! Cryo-ET🔬reveals a large new domain on the small subunit, built from multiple extensions in conserved ribosomal proteins. bioRxiv 📖: shorturl.at/q44tG This suggests greater chlororibosome diversity than expected! 1/n 🧵
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Juan Carlos De la Concepcion @delaconcepcionjc.bsky.social · 30/01/2026
Please share! My group at @zmbp-tuebingen.bsky.social is offering a post-doctoral position (4 years). We look for a structural biologist with experience in Cryo-EM/Cryo-ET to investigate the mechanisms of host invasion by pathogenic fungi. Deadline February 28th! uni-tuebingen.de/universitaet...
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Max Planck Institute of Biochemistry @mpibiochem.bsky.social · 28/01/2026
Formation & function of #MembranelessOrganelles! #CryoET structures of #proteasome storage granules inside cells! Read our paper @cp-cell.bsky.social! ❕Publication: doi.org/10.1016/j.ce... ❕Press Release: www.biochem.mpg.de/en/pressroom @uoftmedicine.bsky.social @erc.europa.eu #UPSmeetMet
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Lorenz Grundmann @lgrundmann.bsky.social · 27/01/2026
Big congratulations and a huge thank you to everyone involved. I am especially greatful for the great collaboration with the shared first author Ying Zhang who was doing the biochemical experiments and handled the yeast.
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Lorenz Grundmann @lgrundmann.bsky.social · 27/01/2026
These findings provide key insight into cotranslational protein folding and proteostasis in eukaryotic cells, resolve the cotranslational cycle of Ssb, and support a unified model integrating prior structural and biochemical data.
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Lorenz Grundmann @lgrundmann.bsky.social · 27/01/2026
Further, we show that initial recruitment of Ssb to the ribosome is independent of direct interaction with RAC but is stabilized by engagement with the NC accompanied by ATP hydrolysis. This is a criminally short summary of many experiments, please check the paper if you want to know more 😜
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Lorenz Grundmann @lgrundmann.bsky.social · 27/01/2026
Point mutations not only verified our model, but also established this as the interface which is engaged by Ssb in the precatalytic ATP bound state and where Ssb in the ADP state remains bound in the post catalytic ADP state.
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Lorenz Grundmann @lgrundmann.bsky.social · 27/01/2026
We identified Rpl25 as the major interaction site, which was resolved to ~4Å. Being able to assign side chains, we further observed several charged interactions governing this interaction. This was our key finding, which allowed us to decipher the early events of the Ssb cotranslational cycle.
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Lorenz Grundmann @lgrundmann.bsky.social · 27/01/2026
We modeled Met-elongator tRNA base pairing to the final AUG codon and the nascent chain in the exit tunnel. Owing to limited Ssb–SBD-β resolution due to flexibility, the bound NC was only apparent in low-pass filtered maps.
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Lorenz Grundmann @lgrundmann.bsky.social · 27/01/2026
Ending up with just ~14K and ~33K particles we solved the structure of RNC-Ssb in the ADP state in two conformations called S1 and S2. Global resolution was estimated at 2.8Å and 3.0Å for S1 and S2 state respectively. Local resolution of the 80S-Ssb interface, however, was limited to 4-10Å.
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Lorenz Grundmann @lgrundmann.bsky.social · 27/01/2026
Therefore, we started to iteratively classify our particles using increasingly tighter masks. Due to our particle numbers dropping fast, we needed a lot of data. Backfilling our Krios queue, we finally collected >54.000 micrographs.
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Lorenz Grundmann @lgrundmann.bsky.social · 27/01/2026
Focusing on this stalled ribosome population, masked classifications began to converge, and we were able to identify the density as Ssb’s C-terminal substrate binding domain (SBD). With <25 kDa the SBD was too small for local refinements severely limiting the local resolution of the SBD.
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Lorenz Grundmann @lgrundmann.bsky.social · 27/01/2026
The silver bullet was to assess global heterogeneity first. We used cryoDRGN and analyzed the landscape analysis. We found that non-rotated ribosomes with a P-site tRNA and a density corresponding to a trailing ribosome (Figure, Cluster 1), were ever so slightly enriched in Ssb occupancy.
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Lorenz Grundmann @lgrundmann.bsky.social · 27/01/2026
In the initial consensus reconstructions, we noted a small, very weak density close to the exit tunnel in low-pass filtered, weakly thresholded maps. Owing to its low occupancy, masked classification in CS or RELION did not permit further subdivision of the particle stack. - Figure not published -
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Lorenz Grundmann @lgrundmann.bsky.social · 27/01/2026
We expressed a truncated Flag-Pgk(1-70) mRNA without a stop codon in a yeast in-vitro system with added recombinant Ssb. Thus, we were able to enrich stalled RNC using the nascent chain's (NC) N-terminal Flag tag and prepare cryoEM grids.
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Lorenz Grundmann @lgrundmann.bsky.social · 27/01/2026
To close this knowledge gap, we turned to the yeast Hsp70 Ssb. First, we (@haselbachlab.bsky.social, @impvienna.bsky.social in collaboration with the Rospert group @uni-freiburg.de ) started working on cryoEM structures of ribosome-nascent-chain-complexes (RNC) cotranslational engaged with Ssb.
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Lorenz Grundmann @lgrundmann.bsky.social · 27/01/2026
Coupling ribosomal translation to cotranslational folding is essential for cellular homeostasis. In eukaryotes, this process relies on Hsp70 and its J-domain cochaperone RAC, but how Hsp70 activity is coordinated with translation remains unclear.
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Lorenz Grundmann @lgrundmann.bsky.social · 27/01/2026
Check out our new paper in @natcomms.nature.com .com where we used #cryoEM together with biochemical and mutational analyses investigated the cotranslational protein folding by Ssb in yeast. Publication: doi.org/10.1038/s41467-025-67685-6 Check below for the cryoEM centric feed. 👇
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Haselbach Lab @haselbachlab.bsky.social · 19/01/2026
Have a look at our new structure of co translational folding in yeast. This is collaborative work initialized by the Rospert lab from the @uni-freiburg.de. Structural work has been done by the amazing @lgrundmann.bsky.social Stay tuned for the next ribosome paper from him, following very soon.
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Haselbach Lab @haselbachlab.bsky.social · 22/01/2026
And the 4th paper in this week contribution from our lab tells about ribosome biogenesis in yeast. A follow-up story from our wonderful collaborators in Graz - the Bergler Lab. Structural work was again done by the amazing @lgrundmann.bsky.social: academic.oup.com/nar/article/...
academic.oup.com
A comprehensive view on r-protein binding and rRNA domain structuring during early eukaryotic ribosome formation
Abstract. Formation of the eukaryotic ribosomal subunits follows a strict regime to assemble ribosomal proteins (r-protein) with ribosomal RNAs (rRNA) whil
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Lorenz Grundmann @lgrundmann.bsky.social · 16/12/2025
I didn't realize. They nonetheless ended up in my stomach - so tasty :)
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Alicia Michael @aliciakmichael.bsky.social · 08/12/2025
One month later and still thinking about the great science and conversations from the 8th Austrian Cryo-EM Symposium 🧊🔬 Huge thanks to all who joined - let’s make next year even bigger! cryoem-symposium.pages.ist.ac.at/invited-spea...
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IMP @impvienna.bsky.social · 06/11/2025
New paper alert! Scientists in Clemens Plaschka’s lab at the IMP and @juliusbrennecke.bsky.social's lab at @imbavienna.bsky.social solved a decade-old puzzle, uncovering how the information molecule mRNA travels from the cell’s nucleus to its periphery. More: bit.ly/4nHcvys
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Julius Brennecke @juliusbrennecke.bsky.social · 07/11/2025
just in time for the opening of the @hohmannulrich.bsky.social group at @imbmainz.bsky.social what started as a project on how cells export piRNA precursors, ended up as a tour de force in mRNA export. truly wonderful collaboration with @plaschkalab.bsky.social at the @viennabiocenter.bsky.social
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Juan Carlos De la Concepcion @delaconcepcionjc.bsky.social · 31/10/2025
My main work as postdoc @plantophagy.bsky.social lab in @gmivienna.bsky.social is out in @natplants.nature.com 🌱🎉 We asked how can protein complexes diversify without compromising their function and explored this question using the plant #exocyst complex. www.nature.com/articles/s41...
nature.com
Electrostatic changes enabled the diversification of an exocyst subunit via protein complex escape - Nature Plants
The evolutionary diversification of an exocyst subunit was enabled by electrostatic shifts leading to its dissociation from the ancestral complex.
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Lorenz Grundmann @lgrundmann.bsky.social · 01/11/2025
Congratulations Juan. Really amazing 🤩
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Lorenz Grundmann @lgrundmann.bsky.social · 15/10/2025
Fair. It is just easier for me to believe that someone tries to get away with something like this than someone actually getting away with it (for now at least). Mind boggling.
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Lorenz Grundmann @lgrundmann.bsky.social · 15/10/2025
Whatever happened here cannot be called peer review imo. I don't know who did worse - the authors or the "reviewers". They even show the frickin map in a main figure. Crazy that many excellent papers in Structure have to stand next to something like this.
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joe dobbs @joedobbs.bsky.social · 15/10/2025
Check out our preprint! With new molecular mechanisms, 140 subtomogram averages, and ~600 annotated cells under different conditions, we @embl.org were able to describe bacterial populations with in-cell #cryoET. And there’s a surprise at the end 🕵️ www.biorxiv.org/content/10.1... #teamtomo
Figure 1 from the preprint
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Ulrich Hohmann @hohmannulrich.bsky.social · 12/10/2025
Thrilled to share that I’ll be joining @imbmainz.bsky.social in February 2026 to start my own group! We will explore new mechanisms in eukaryotic gene expression, leveraging ‘evolutionary play’ to uncover how regulation, repurposing, and hijacking shape RNA biology. PhD positions available!
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Institute of Science and Technology Austria (ISTA) @istaresearch.bsky.social · 10/10/2025
Join us for the Austrian Cryo-EM Symposium from Nov 11–12 at ISTA! Top speakers, cutting-edge cryo-EM, and a chance to explore Vienna & the ISTA campus. Register now 👉 cryoem-symposium.pages.ist.ac.at/registration/ #cryoEM
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Lorenz Grundmann @lgrundmann.bsky.social · 11/10/2025
... or a 30S proteasome.
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Lorenz Grundmann @lgrundmann.bsky.social · 11/10/2025
The last one looks like a 26S proteasome (~350Å long) to me. The one before that also seems to be a proteasomal assembly. Hard to say which one but could be a hybrid proteasome (19S one one side of the 20S and PA200 or PA28 on the other side).
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Kresten Lindorff-Larsen @lindorfflarsen.bsky.social · 07/10/2025
A good day to remember John Gurdon’s school report from his biology master at Eton
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Ulrich Hohmann @hohmannulrich.bsky.social · 23/09/2025
How are RNAs sorted for export vs. degradation in the nucleus? In collaboration with @heick.bsky.social’s lab we (@clemensplaschka.bsky.social and @juliusbrennecke.bsky.social labs) discovered a direct mechanistic link between the export and decay machineries: www.biorxiv.org/content/10.1... (1/x)
biorxiv.org
Molecular basis of polyadenylated RNA fate determination in the nucleus
Eukaryotic genomes generate a plethora of polyadenylated (pA+) RNAs[1][1],[2][2], that are packaged into ribonucleoprotein particles (RNPs). To ensure faithful gene expression, functional pA+ RNPs, in...
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Laura Lorenzo Orts @lorenzoorts.bsky.social · 15/09/2025
I am excited to announce that I will be moving to IMB Mainz next year! The Winter call for the IPP PhD program is now open; if you are interested in maternal #mRNA regulation and #translation in early vertebrate development, please apply! Deadline: 16 October. More info: www.imb.de/students-pos...
imb.de
Laura Lorenzo Orts
IMB Mainz
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Lorenz Grundmann @lgrundmann.bsky.social · 02/09/2025
Makes sense, thanks for the explanation 🙂 Looking forward to play around with it once available on EMPIAR. It seems ideal to get a grasp on the processing of (pseudo)symmetric complexes with symmetrie breaking interaction partners.
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Lorenz Grundmann @lgrundmann.bsky.social · 01/09/2025
I was surprised to see that the classification was that complicated. Did you try refinement and 3D classifications with or without image alignment in C1 before refining in C16? Either way this is such a cool processing problem resulting in such a cool structure and story. Much congrats!
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Dan Grabarczyk @dangrabarczyk.bsky.social · 28/08/2025
Glad to share the final version of our story about the UBR4 complex, an E4 ligase protein quality control hub @science.org. Now with more cryo-EM structures and a deeper dive into substrate recognition, especially escaped mitochondrial proteins @clausenlab.bsky.social www.science.org/doi/10.1126/...
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