The E3 ubiquitin ligase mechanism specifying target-directed microRNA degradation (TDMD) is now published! 🎉🍾 We, @bartellab.bsky.social and Schulman lab, describe how 2-RNA factors control protein degradation by recruiting an E3 ligase. @mpibiochem.bsky.social
www.nature.com/articles/s41...

A CK2-FBXW11 kinase-E3 ubiquitin ligase cascade is a metabolic sensor regulating Tryptophan 2,3-dioxygenase stability Small molecules toggling the ubiquitin-proteasome system (UPS) are powerful regulators of protein degradation. Yet, mechanistic knowledge of how endogenous ligands gate UPS decisions remains rudimentary. Here, we define control of UPS access to Tryptophan-2,3-dioxygenase (TDO2), which converts the essential amino acid tryptophan (Trp) to N-formylkynurenine. When Trp concentrations are limiting, TDO2 is degraded to avert tryptophanemia. Using CRISPRi screening and biochemistry, we identify a CK2-FBXW11 kinase-E3 ligase cascade that generates and recognizes tandem TDO2 phosphodegrons when not protected by Trp. Trp binding to an exosite safeguards TDO2 from phosphorylation-dependent ubiquitylation. Effects of Trp analogs on CK2-FBXW11-dependent ubiquitylation indicated that the indole, amino, and carboxylate groups are necessary for substrate shielding. Cryo-EM reveals how these moieties order a region proximal to the phosphodegrons; without Trp, this segment is flexible, enabling phosphorylation-coupled ubiquitylation. Overall, our data uncovered an endogenous small molecule allosterically stabilizing its own metabolizing enzyme through protection from a phosphorylation-ubiquitylation cascade. ### Competing Interest Statement B.A.S. is a member of the scientific advisory boards of Proxygen and Lyterian. The other authors declare no competing interests. Max Planck Society, https://ror.org/01hhn8329 European Union, ERC AdvG, UPSmeetMet, 101098161 to BAS Boehringer Ingelheim Fonds, https://ror.org/00dkye506

New year, new preprint! 🎊

We are excited to share our recent work on #E3 ligase regulation in #metabolism!

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

#ubiquitin #targetedproteindegradation #chemicalbiology

1/6

Fantastic work! Congratulations Max!