Gp120 on HIV-1 Virions Lacks O-Linked Carbohydrate.
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.
New England Primate Research Center, Harvard Medical School, Southborough, Massachusetts, 01772, United States of America.
Elizabeth
E
Stansell
Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom.
Maria
M
Panico
Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom.
Kevin
K
Canis
Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom.
Poh-Choo
PC
Pang
Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom.
Laura
L
Bouché
MS-RTC (Mass Spectrometry Research and Training Centre), Suite 3.1 Lido Medical Centre, St. Saviours Road, Jersey, JE2 7LA, United Kingdom.
Daniel
D
Binet
MS-RTC (Mass Spectrometry Research and Training Centre), Suite 3.1 Lido Medical Centre, St. Saviours Road, Jersey, JE2 7LA, United Kingdom.
Michael-John
MJ
O'Connor
AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, Maryland, 21702, United States of America.
Elena
E
Chertova
AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, Maryland, 21702, United States of America.
Julian
J
Bess
AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, Maryland, 21702, United States of America.
Jeffrey D
JD
Lifson
Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom.
Stuart M
SM
Haslam
Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom; MS-RTC (Mass Spectrometry Research and Training Centre), Suite 3.1 Lido Medical Centre, St. Saviours Road, Jersey, JE2 7LA, United Kingdom.
Howard R
HR
Morris
New England Primate Research Center, Harvard Medical School, Southborough, Massachusetts, 01772, United States of America.
Ronald C
RC
Desrosiers
Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom.
Anne
A
Dell
D002241:Carbohydrates / Q000737:chemistry*; D057809:HEK293 Cells; D015699:HIV Envelope Protein gp120 / Q000737:chemistry* / Q000235:genetics*; D015497:HIV-1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D009980:Influenza A virus / Q000737:chemistry / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000737:chemistry; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013912:Threonine / Q000737:chemistry*; D014759:Viral Envelope Proteins / Q000737:chemistry; D014771:Virion / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D002241:Carbohydrates; D015699:HIV Envelope Protein gp120; D008562:Membrane Glycoproteins; D011994:Recombinant Proteins; D014759:Viral Envelope Proteins; C514793:gp120 protein, Human immunodeficiency virus 1; C069623:gp120 protein, Simian immunodeficiency virus; D013912:Threonine