8W1A

Cryo-EM Structure of KSHV ORF74 Apo Dimer at 2.8A

Summary for 8W1A

• Entry DOI: 10.2210/pdb8w1a/pdb
• EMDB information: 43717
• Descriptor: viral G-protein coupled receptor (1 entity in total)
• Functional Keywords: kshv vgpcr, viral gpcr, kshv orf74, orf74 apo, orf74 inactive, viral protein
• Biological source: Human gammaherpesvirus 8
• Total number of polymer chains: 2
• Total formula weight: 84264.53

Authors

Sahoo, B.,Seo, H.D.,Dai, X.,Jung, J. (deposition date: 2024-02-15, release date: 2025-08-27, Last modification date: 2025-10-08)

Primary citation

Park, J.B.,Sahoo, B.,Sahoo, A.R.,Kim, D.,Seo, H.D.,Bowman, J.,Kwak, M.J.,Suh, S.,Buck, M.,Dai, X.,Jung, J.U.
Structural basis for ligand promiscuity and high signaling activity of Kaposi's Sarcoma-associated Herpesvirus-encoded GPCR.
Nat Commun, 16:8403-8403, 2025

PubMed Abstract: Kaposi's Sarcoma-associated Herpesvirus encodes ORF74, a viral G protein-coupled receptor homologous to CXCR2, which plays a crucial role in Kaposi's Sarcoma development through its high basal signaling activity. Our cryoEM analysis of ORF74 in ligand-free, BRIL-fused ligand-free, and CXCL1/Gi-bound forms elucidates its ligand-independent signaling activity. A widely open, static extracellular cavity facilitates ligand promiscuity by enabling dynamic access and diverse binding modes. Structural alterations in CWxP, E/DRY, and NPxxY micro-switches stabilize the active conformation, leading to constitutive signaling. Metadynamics simulations reveal a dynamic ensemble between local switch structures corresponding to the inactive and active states, supporting spontaneous activation. CXCR2-ORF74 chimeras highlight intracellular loops 2 and 3 as key modulators of basal and agonist-induced activity. This study defines the structural basis of ORF74's ligand promiscuity, spontaneous activation, and high basal signaling, providing insights into its role in viral oncogenesis.

PubMed: 40998787
DOI: 10.1038/s41467-025-63457-4

Experimental method

ELECTRON MICROSCOPY (2.89 Å)