Biophysical Society Conference | Tahoe 2024

Molecular Biophysics of Membranes

Wednesday Speaker Abstracts

19 F-QNMR-ASSISTED STRUCTURAL ELUCIDATION OF A LIGAND-FREE GPCR-G PROTEIN INTERMEDIATE COMPLEX Libin Ye 3,4 ; Maxine Bi 1 ; Xudong Wang 3 ; Jinan Wang 2 ; Wenkai Sun 3 ; Victor Ayo Adediwura 2 ; Yinglong Miao 2 ; Yifan Cheng 1 ; 1 University of California San Francisco, Biochemistry and Biophysics, San Francisco, CA, USA 2 University of North Carolina, Chapel Hill, Pharmacology & Computational Medicinal Program, Chapel Hill, NC, USA 3 University of South Florida, Molecular Biosciences, Tampa, FL, USA 4 Moffitt Cancer Center, Tampa, FL, USA Despite the cryo-EM revolution leading to the resolution of over 500 GPCR- Gαβγ complex structures, these snapshots primarily capture the fully activated end-state. Consequently, a comprehensive understanding of the conformational transitions during GPCR activation and the roles of intermediates in signal transduction remains elusive. Herein, creation of an intermediate state-trapped mutant, guided by 19 F quantitative NMR ( 19 F-qNMR) and Molecular Dynamics (MD) simulations 1 , facilitated sampling of a homogeneous intermediate state in the adenosine A 2A receptor (A 2A R). This approach yielded a high-resolution cryo-EM structure of intermediate ligand-free (apo) GPCR- Gαβγ complex, via the strategy of blocking conformational transition to the fully activated state. This advancement fills critical structural gap of intermediate complex in the course of GPCR signaling.

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