Gp120 on HIV-1 Virions Lacks O-Linked Carbohydrate.

Authors:
Mr Daniel Binet
Mr Daniel Binet
BioPharmaSpec Ltd/MS-RTC (Mass Spectrometry Research and Training Centre)
Director of Operations
LC-MS, LC-MS/MS, GC-MS, cIEF, Gas Phase Sequencing
St Saviour, Jersey | United Kingdom

PLoS One 2015 27;10(4):e0124784. Epub 2015 Apr 27.

Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom.

As 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.

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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0124784PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4410959PMC
January 2016
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CK Leonard et al.
J Biol Chem 1990
Studies on the attachment of carbohydrate to ovalbumin nascent chains in hen oviduct
ML Kiely et al.
J Biol Chem 1976

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