HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 ENVELOPE GLYCOPROTEIN IS MODIFIEDBY O-LINKED OLIGOSACCHARIDES

The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein has been shown to be extensively modified by N-linked glycosylation; h owever, the presence of O-linked carbohydrates on the glycoprotein has not been firmly established. We have found that enzymatic deglycosyla tion of the HIV-1 envelope glycoprotein with neuraminidase and O-glyco sidase results in a decrease in the apparent molecular weight of the e nvelope glycoprotein. This result was observed in both vaccinia virus recombinant-derived envelope glycoproteins and glycoproteins derived f rom the IIIB, SG3, and HIV2, strains of HIV-1. The decrease in molecul ar weight was also observed when the envelope glycoprotein had been de glycosylated with N-glycanase F after treatment with neuraminidase and O-glycosidase, indicating that the decrease in apparent molecular wei ght was not attributable to the removal of N-linked carbohydrate. Trea tment with neuraminidase, O-glycosidase, and N-glycanase F was found t o be necessary to remove all radiolabel from [H-3] glucosamine-labelle d envelope glycoprotein, a result seen for both recombinant and HIV-1- derived envelope glycoprotein. [H-3]glucosamine-labelled carbohydrates liberated by O-glycosidase treatment were separated by paper chromato graphy and were found to be of a size consistent with O-linked oligosa ccharides. We, therefore, conclude that the HIV-1 envelope glycoprotei n is modified by the addition of O-linked carbohydrates.