Stansell, ElizabethPanico, MariaCanis, KevinPang, Poh-ChooBouché, LauraBinet, DanielO'Connor, Michael-JohnChertova, ElenaBess, JulianLifson, Jeffrey D.Haslam, Stuart M.Morris, Howard R.Desrosiers, RonaldDell, Anne2015-06-022015Stansell, E., M. Panico, K. Canis, P. Pang, L. Bouché, D. Binet, M. O'Connor, et al. 2015. “Gp120 on HIV-1 Virions Lacks O-Linked Carbohydrate.” PLoS ONE 10 (4): e0124784. doi:10.1371/journal.pone.0124784. http://dx.doi.org/10.1371/journal.pone.0124784.1932-6203http://nrs.harvard.edu/urn-3:HUL.InstRepos:16121092As HIV-1-encoded envelope protein traverses the secretory pathway, it may be modified with N- and O-linked carbohydrate. When the gp120s of HIV-1 NL4-3, HIV-1 YU2, HIV-1 Bal, HIV-1 JRFL, and HIV-1 JRCSF were expressed as secreted proteins, the threonine at consensus position 499 was found to be O-glycosylated. For SIVmac239, the corresponding threonine was also glycosylated when gp120 was recombinantly expressed. Similarly-positioned, highly-conserved threonines in the influenza A virus H1N1 HA1 and H5N1 HA1 envelope proteins were also found to carry O-glycans when expressed as secreted proteins. In all cases, the threonines were modified predominantly with disialylated core 1 glycans, together with related core 1 and core 2 structures. Secreted HIV-1 gp140 was modified to a lesser extent with mainly monosialylated core 1 O-glycans, suggesting that the ectodomain of the gp41 transmembrane component may limit the accessibility of Thr499 to glycosyltransferases. In striking contrast to these findings, gp120 on purified virions of HIV-1 Bal and SIV CP-MAC lacked any detectable O-glycosylation of the C-terminal threonine. Our results indicate the absence of O-linked carbohydrates on Thr499 as it exists on the surface of virions and suggest caution in the interpretation of analyses of post-translational modifications that utilize recombinant forms of envelope protein.en-USJournal Article2015-06-0210.1371/journal.pone.0124784