Evaluating the Topological Features of Monomeric and Trimeric TRAF2-C: A Multi-Disciplinary Approach

This study investigates the structural dynamics of the TRAF2 C-terminal domain (TRAF2-C), a key adaptor protein in TNF receptor signaling. TRAF2 usually forms trimers, but its ability to dissociate into monomers is critical for regulating apoptosis, inflammation, and cell survival. Using Fluorescence Fluctuation Spectroscopy, dynamic light scattering, circular dichroism, and Small Angle Neutron Scattering, we analyzed TRAF2-C over a wide concentration range. At nanomolar levels, the protein dissociates easily, with trimers representing only a minor fraction, while micromolar concentrations strongly favor trimerization. Dissociation also reduces α-helical content without disrupting the overall fold. Molecular dynamics simulations and protein contact network analysis support this analysis, identifying interfacial residues and hydrogen bonds as key factors stabilizing oligomers and enabling dynamic asymmetry. Overall, these findings highlight TRAF2-C's capacity to switch between monomeric and trimeric states as a crucial regulatory mechanism, offering insights into TRAF-mediated signaling and potential therapeutic strategies.