ROLE OF N-LINKED GLYCOSYLATION IN THE ACTIVITY OF THE FRIEND MURINE LEUKEMIA-VIRUS SU PROTEIN RECEPTOR-BINDING DOMAIN

The 243 N-terminal residues of Friend Murine Leukemia Virus envelope g lycoprotein (SU) fold into a structurally and functionally autonomous domain which contains the determinants for binding to the ecotropic vi rus receptor. The two N-linked glycosylation sites present in this N-t erminal portion of the viral SU were removed by site-directed mutagene sis without disturbing its biosynthesis and incorporation into infecti ous virions, A truncated version of the mutant protein which included only the N-terminal domain was poorly transported but still able to in teract with the receptor. Interference assays indicated that the inter action between the mutated protein and the virus receptor was weaker. We conclude that the elimination of N-linked oligosaccharide chains in the envelope N-terminal domain do not prevent receptor interaction bu t results in subtle conformational changes that may alter recognition and binding. (C) 1994 Academic Press, Inc.