Proteins carry out most cell functions and thus it is important to understand protein dynamics, in practice, knowing how they fold and how they interact. Within the framework of energy landscape theory and the funnel concept, we used domain swapping as an example of protein interaction to demonstrate the physical principles that underlie protein interaction and aggregation. As a direct biological implication, a novel structural model for the infectious prion was proposed under the name of "domain- swapping trimeric prion". Along the line of course-grained modeling for protein interaction, we also utilized atomic simulations to study the detail of folding dynamics using beta-hairpin as a model system. To reduce the high- dimensional folding problem, we introduced an "effective stochastic dynamics" approach to characterize the folding kinetics by using one or two functional reaction coordinates. This method provides a general framework to understand the dynamics of relevant biological systems

Chemokines drive cell migration through their interactions with seven-transmembrane (7TM) chemokine receptors on cell surfaces. The atypical chemokine receptor 3 (ACKR3) binds chemokines CXCL11 and CXCL12 and signals exclusively through β-arrestin-mediated pathways, without activating canonical G-protein signalling. This receptor is upregulated in numerous cancers making it a potential drug target. Here we collected over 100 distinct structural probes from radiolytic footprinting, disulfide trapping, and mutagenesis to map the structures of ACKR3:CXCL12 and ACKR3:small-molecule complexes, including dynamic regions that proved unresolvable by X-ray crystallography in homologous receptors. The data are integrated with molecular modelling to produce complete and cohesive experimentally driven models that confirm and expand on the existing knowledge of the architecture of receptor:chemokine and receptor:small-molecule complexes. Additionally, we detected and characterized ligand-induced conformational changes in the transmembrane and intracellular regions of ACKR3 that elucidate fundamental structural elements of agonism in this atypical receptor.

Human estrogen receptor alpha (hERα) is a hormone-responsive nuclear receptor (NR) involved in cell growth and survival that contains both a DNA-binding domain (DBD) and a ligand-binding domain (LBD). Functionally relevant inter-domain interactions between the DBD and LBD have been observed in several other NRs, but for hERα, the detailed structural architecture of the complex is unknown. By utilizing integrated complementary techniques of small-angle X-ray scattering, hydroxyl radical protein footprinting and computational modeling, here we report an asymmetric L-shaped "boot" structure of the multidomain hERα and identify the specific sites on each domain at the domain interface involved in DBD-LBD interactions. We demonstrate the functional role of the proposed DBD-LBD domain interface through site-specific mutagenesis altering the hERα interfacial structure and allosteric signaling. The L-shaped structure of hERα is a distinctive DBD-LBD organization of NR complexes and more importantly, reveals a signaling mechanism mediated by inter-domain crosstalk that regulates this receptor's allosteric function.