Welcome Dr. Aamir Mehmood to join Miao Lab as a Postdoctoral Research Associate!
Abstract
Adhesion G protein鈥揷oupled receptors (ADGRs) belong to Class B2 of GPCRs and are involved in a wide array of important physiological processes. ADGRs contain a GPCR autoproteolysis-inducing domain that is proximal to the receptor N-terminus and undergoes autoproteolysis during the biosynthesis to generate two fragments: the N-terminal fragment (NTF) and the C-terminal fragment (CTF). Dissociation of NTF reveals a tethered agonist to activate the CTF of ADGRs for G protein signaling. Synthetic peptides that mimic the tethered agonist can also activate ADGRs. However, mechanisms of peptide agonist dissociation and the deactivation of ADGRs remain poorly understood. In this study, we have performed all-atom enhanced sampling simulations using a novel protein鈥損rotein interaction Gaussian-accelerated molecular dynamics (PPI-GaMD) method on the ADGRG2-IP15 and ADGRG1-P7 complexes. The PPI-GaMD simulations captured the dissociation of the IP15 and P7 peptide agonists from their target receptors. We were able to identify important low-energy conformations of ADGRG2 and ADGRG1 in the active, intermediate, and inactive states, as well as different states of the peptide agonists IP15 and P7 during dissociation. Therefore, our PPI-GaMD simulations have revealed dynamic mechanisms of peptide agonist dissociation and deactivation of ADGRG1 and ADGRG2, which will facilitate the rational design of peptide regulators of the two receptors and other ADGRs.
Abstract
Unraveling the signaling roles of intermediate complexes is pivotal for G protein-coupled receptor (GPCR) drug development. Despite hundreds of GPCR-G伪尾纬 structures, these snapshots primarily capture the fully activated complex. Consequently, the functions of intermediate GPCR-G protein complexes remain elusive. Guided by a conformational landscape visualized via聽19F quantitative NMR and molecular dynamics (MD) simulations, we determined the structure of an intermediate GPCR-mini-G伪s尾纬 complex at 2.6鈥壝� using cryo-EM, by blocking its transition to the fully activated complex. Furthermore, we present direct evidence that the complex at this intermediate state initiates a rate-limited nucleotide exchange before transitioning to the fully activated complex. In this state, BODIPY-GDP/GTP based nucleotide exchange assays further indicated the 伪-helical domain of the G伪 is partially open, allowing it to grasp a nucleotide at a non-canonical binding site, distinct from the canonical nucleotide-binding site. These advances bridge a significant gap in our understanding of the complexity of GPCR signaling.