Background: In recent years, compounds known as Proteolysis Targeted Chimeras (PROTACs) have revitalized the field of bioactive molecule design. These compounds promote proteolysis of therapeutic targets by recruiting them to ubiquitin ligases. One of the most commonly used classes of compounds in the synthesis of PROTACs are immunomodulatory imides (IMiDs), such as thalidomide (TLD), which interact with the E3 ligase CRL4^CRBN via the CULT domain of the cereblon protein (CRBN). This domain has been identified in proteins across various phylogenetic groups, including trypanosomatids, leading to the hypothesis that IMiD-derived PROTACs should be active in these organisms. Methods: The trypanocidal activity of the PROTAC dBET1 and its separated components (JQ1 and TLD) were assayed using a T. cruzi strain expressing β-glalactosidase. Potential CRL4-E3L complexes from humans and trypanosomatids were assembled in silico with MultimerMapper. The IMiD-binding site of HsCRBN and its trypanosomatid homologs were analyzed using molecular dynamics and docking simulations. Results: We demonstrate that the compound dBET1 does not function as a PROTAC in Trypanosoma cruzi. In silico structural analysis of CRL4-E3L complex orthologs revealed that the trypanosomal CULT-containing protein is not part of such a complex. Molecular dynamics simulations showed that the pocket of this CULT domain is smaller than that of mammalian CRBN and cannot accommodate IMiDs within. Conclusions: We underscore the importance of functional and structural validation in drug discovery, particularly when extrapolating mechanisms between evolutionarily distant species. While PROTACs hold promise in human therapeutics, our work advocates for re-evaluating the rationale behind thalidomide-based PROTACs in trypanosomatid research.

MolecularWebXR is our new website for education, science communication and scientific peer discussion in chemistry and biology built on WebXR. It democratizes multi-user, inclusive virtual reality (VR) experiences that are deeply immersive for users wearing high-end headsets, yet allow participation by users with consumer devices such as smartphones, possibly inserted into cardboard goggles for immersivity, or even computers or tablets. With no installs as it is all web-served, MolecularWebXR enables multiple users to simultaneously explore, communicate and discuss chemistry and biology concepts in immersive 3D environments, manipulating objects with their bare hands, either present in the same real space or scattered throughout the globe thanks to built-in audio features. A series of preset rooms cover educational material on chemistry and structural biology, and an empty room can be populated with material prepared ad hoc using moleculARweb's VMD-based PDB2AR tool. We verified ease of use and versatility by users aged 12-80 in entirely virtual sessions or mixed real-virtual sessions at science outreach events, student instruction, scientific collaborations, and conference lectures. MolecularWebXR is available for free use without registration at https://molecularwebxr.org, and a blog post version of this preprint with embedded videos is available at https://go.epfl.ch/molecularwebxr-blog-post.