Bohl, ChristopherBowder, DaneThompson, JesseAbrahamyan, LevonGonzalez-Ramirez, SandraMao, YoudongSodroski, JosephWood, CharlesXiang, Shi-hua2014-03-012013Bohl, Christopher, Dane Bowder, Jesse Thompson, Levon Abrahamyan, Sandra Gonzalez-Ramirez, Youdong Mao, Joseph Sodroski, Charles Wood, and Shi-hua Xiang. 2013. “A Twin-Cysteine Motif in the V2 Region of gp120 Is Associated with SIV Envelope Trimer Stabilization.” PLoS ONE 8 (7): e69406. doi:10.1371/journal.pone.0069406. http://dx.doi.org/10.1371/journal.pone.0069406.1932-6203http://nrs.harvard.edu/urn-3:HUL.InstRepos:11855743The V1 and V2 variable regions of the primate immunodeficiency viruses contribute to the trimer association domain of the gp120 exterior envelope glycoprotein. A pair of V2 cysteine residues at 183 and 191 (“twin cysteines”) is present in several simian immunodeficiency viruses, human immunodeficiency virus type 2 (HIV-2) and some SIVcpz lineages, but not in HIV-1. To examine the role of this potentially disulfide-bonded twin-cysteine motif, the cysteine residues in the SIVmac239 envelope glycoproteins were individually and pairwise substituted by alanine residues. All of the twin-cysteine mutants exhibited decreases in gp120 association with the Env trimer, membrane-fusing activity, and ability to support virus entry. Thus, the twin-cysteine motif plays a role in Env trimer stabilization in SIV and may do so in HIV-2 and some SIVcpz as well. This implies that HIV-1 lost the twin-cysteines, and may have relatively unstable Env trimers compared to SIV and HIV-2.en-USBiologyImmunologyImmune ResponseMicrobiologyVirologyViral ClassificationRetrovirusesViral StructureViral EnvelopeImmunodeficiency VirusesViral EvolutionViral Immune EvasionViral VaccinesMolecular Cell BiologyJournal Article2014-03-0110.1371/journal.pone.0069406