Simian immunodeficiency virus from the sooty mangabey and rhesus macaque is modified with O-linked carbohydrate.
Although stretches of serine and threonine are sometimes sites for O-linked carbohydrate attachment, specific sequence and structural determinants for O-linked attachment remain ill defined. The gp120 envelope protein of SIVmac239 contains a serine-threonine-rich stretch of amino acids at positions 128 to 139. Here we show that lectin protein from jackfruit seed (jacalin), which binds to non- and monosialylated core 1 O-linked carbohydrate, potently inhibited the replication of SIVmac239. Selection of a jacalin-resistant SIVmac239 variant population resulted in virus with specific substitutions within amino acids 128 to 139. Cloned simian immunodeficiency virus (SIV) variants with substitutions in the 128-to-139 region had infectivities equivalent to, or within 1 log unit of, that of SIVmac239 and were resistant to the inhibitory effects of jacalin. Characterization of the SIVmac239 gp120 O-linked glycome showed the presence of core 1 and core 2 O-linked carbohydrate; a 128-to-139-substituted variant gp120 from jacalin-resistant SIV lacked O-linked carbohydrate. Unlike that of SIVmac239, the replication of HIV-1 strain NL4-3 was resistant to inhibition by jacalin. Purified gp120s from four SIVmac and SIVsm strains bound jacalin strongly in an enzyme-linked immunosorbent assay, while nine different HIV-1 gp120s, two SIVcpz gp120s, and 128-to-139-substituted SIVmac239 gp120 did not bind jacalin. The ability or inability to bind jacalin thus correlated with the presence of the serine-threonine-rich stretch in the SIVmac and SIVsm gp120s and the absence of such stretches in the SIVcpz and HIV-1 gp120s. Consistent with sequence predictions, two HIV-2 gp120s bound jacalin, while one did not. These data demonstrate the presence of non- and monosialylated core 1 O-linked carbohydrate on the gp120s of SIVmac and SIVsm and the lack of these modifications on HIV-1 and SIVcpz gp120s.
New England Primate Research Center, Harvard Medical School, Southborough, MA 01772-9102, USA.
Elizabeth
E
Stansell
Kevin
K
Canis
Stuart M
SM
Haslam
Anne
A
Dell
Ronald C
RC
Desrosiers
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D031622:Artocarpus / Q000737:chemistry; D002241:Carbohydrates / Q000737:chemistry*; D016665:Cercocebus atys / Q000821:virology*; D024882:Drug Resistance, Viral; D015699:HIV Envelope Protein gp120 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015497:HIV-1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008253:Macaca mulatta / Q000821:virology*; D008969:Molecular Sequence Data; D037121:Plant Lectins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D016097:Simian Acquired Immunodeficiency Syndrome / Q000821:virology; D015302:Simian Immunodeficiency Virus / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D002241:Carbohydrates; D015699:HIV Envelope Protein gp120; D037121:Plant Lectins; C043696:jacalin