9SV8

Herpes simplex virus 2 delta28-73 glycoprotein C ectodomain in complex with C3b

Summary for 9SV8

• Entry DOI: 10.2210/pdb9sv8/pdb
• EMDB information: 55245
• Descriptor: Envelope glycoprotein C, Complement C3 beta chain, Complement C3b alpha' chain (3 entities in total)
• Functional Keywords: protein complex, domains 1 and 2 of gc2 with c3b., viral protein
• Biological source: Human alphaherpesvirus 2; More
• Total number of polymer chains: 3
• Total formula weight: 227212.80

Authors

Rojas Rechy, M.H.,Atanasiu, D.,Hook, L.M.,Cairns, M.T.,Saw, W.T.,Cahill, A.,Guo, Z.,Calabrese, A.N.,Ranson, N.A.,Friedman, H.M.,Cohen, G.H.,Fontana, J. (deposition date: 2025-10-02, release date: 2025-12-10)

Primary citation

Rojas Rechy, M.H.,Atanasiu, D.,Hook, L.M.,Cairns, T.M.,Saw, W.T.,Cahill, A.,Guo, Z.,Calabrese, A.N.,Ranson, N.A.,Friedman, H.M.,Cohen, G.H.,Fontana, J.
Unveiling the unique interaction mechanism of herpes simplex virus 2 glycoprotein C with C3b.
Biorxiv, 2025

PubMed Abstract: The complement cascade is part of the first line of defence against viral infections, and many viruses have evolved to block it. For example, glycoprotein C (gC) from Herpes Simplex Virus 1 and 2 (gC1 and gC2) facilitates infection by modulating the complement cascade through an interaction with C3b. gC is also involved in attachment and other viral processes. However, our understanding of the molecular mechanisms of gC have been limited due to the absence of a structure. AlphaFold predicts that gC contains a disordered N-terminus and three immunoglobulin-like domains. Here, we generated various gC2 constructs and demonstrated that gC2 domains 1 and 2 are necessary and sufficient to interact with C3b and block the alternative pathway. A gC2 construct lacking the N-terminus in complex with C3b was characterised by cryo-EM at 3.6 Å, providing the first structure for gC2, and revealing that the interaction is predominantly driven by gC2 domain 2 and the MG8 domain of C3b. This structure was confirmed by cross-linking mass spectrometry and by using C3b-blocking antibodies that recognised gC2 linear epitopes at the interface with C3b. Overall, the gC-C3b interaction is different from other C3b-interacting partners, providing a novel mechanism to regulate the complement cascade.

PubMed: 41256425
DOI: 10.1101/2025.10.04.680448

Experimental method

ELECTRON MICROSCOPY (3.56 Å)