Structure of unliganded HSV gD reveals a mechanism for receptor-mediated activation of virus entry.
Krummenacher, C., Supekar, V.M., Whitbeck, J.C., Lazear, E., Connolly, S.A., Eisenberg, R.J., Cohen, G.H., Wiley, D.C., Carfi, A.(2005) EMBO J 24: 4144-4153
- PubMed: 16292345 
- DOI: https://doi.org/10.1038/sj.emboj.7600875
- Primary Citation of Related Structures:  
2C36, 2C3A - PubMed Abstract: 
Herpes simplex virus (HSV) entry into cells requires binding of the envelope glycoprotein D (gD) to one of several cell surface receptors. The 50 C-terminal residues of the gD ectodomain are essential for virus entry, but not for receptor binding. We have determined the structure of an unliganded gD molecule that includes these C-terminal residues. The structure reveals that the C-terminus is anchored near the N-terminal region and masks receptor-binding sites. Locking the C-terminus in the position observed in the crystals by an intramolecular disulfide bond abolished receptor binding and virus entry, demonstrating that this region of gD moves upon receptor binding. Similarly, a point mutant that would destabilize the C-terminus structure was nonfunctional for entry, despite increased affinity for receptors. We propose that a controlled displacement of the gD C-terminus upon receptor binding is an essential feature of HSV entry, ensuring the timely activation of membrane fusion.
Organizational Affiliation: 
Department of Microbiology, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, USA.