Max Bonomi

@bonomimax.bsky.social

Head of Computational Structural Biology Lab @pasteur.fr. ERC-CoG 2022. Research Director DR2 @cnrs.bsky.social. Founder/developer @plumed.org

❄️ Even high-resolution #cryoEM maps can still hide a few secrets 🔍 Discover how we uncover them in this exciting collaboration with @egreene.bsky.social @fraserlab.com @pasteur.fr @cnrsbiologie.bsky.social 📄 Preprint: www.biorxiv.org/content/10.1...

Product-stabilized filamentation by human glutamine synthetase allosterically tunes metabolic activity

To maintain metabolic homeostasis, enzymes must adapt to fluctuating nutrient levels through mechanisms beyond gene expression. Here, we demonstrate that human glutamine synthetase (GS) can reversibly polymerize into filaments aided by a composite binding site formed at the filament interface by the product, glutamine. Time-resolved cryo-electron microscopy (cryo-EM) confirms that glutamine binding stabilizes these filaments, which in turn exhibit reduced catalytic specificity for ammonia at physiological concentrations. This inhibition appears induced by a conformational change that remodulates the active site loop ensemble gating substrate entry. Metadynamics ensemble refinement revealed >10 Å conformational range for the active site loop and that the loop is stabilized by transient contacts. This disorder is significant, as we show that the transient contacts which stabilize this loop in a closed conformation are essential for catalysis both in vitro and in cells. We propose that GS filament formation constitutes a negative-feedback mechanism, directly linking product concentration to the structural and functional remodeling of the enzyme. ### Competing Interest Statement HY is an employee of JSR. J.S.F. is a consultant to, a shareholder of, and receives sponsored research support from Relay Therapeutics. National Institutes of Health, https://ror.org/01cwqze88, F32GM144982, R35GM145238

biorxiv.org

AlphaFold’s success builds on decades of tech advances, massive efforts to collect, curate, and share structural data, and rigorous benchmarking. What will it take to see a similar leap in structural ensemble prediction? @stephanieaw.bsky.social and I share some thoughts here 👇 Feedback is welcome!

Stephanie Wankowicz@stephanieaw.bsky.social · last yr.

Predicting macromolecular ensembles is incredibly promising. However, as no single experimental method can map a conformational ensemble’s full atomistic landscape, there are foundational questions: What exactly are we trying to predict, and how will we know when we have succeeded?