Role of oligosaccharides in the structure and function of respiratory syncytial virus glycoproteins.
The contribution of oligosaccharides to the structural and functional make-up of respiratory syncytial (RS) virus G and F proteins was investigated by observing the effects of various oligosaccharide-specific enzymes on their molecular size as well as on virus infectivity. The N-linked oligosaccharides of the F protein were completely removed by endoglycosidase F and N-glycanase. Addition of oligosaccharides to F protein during synthesis was completely inhibited by the drug tunicamycin (TM), an inhibitor of N-linked glycosylation. Glycosylation of the G protein was partially resistant to TM resulting in an 80-kDa form designated GTM. The G protein was estimated to contain approximately 3% N-linked and 55% O-linked carbohydrates, based on migration of G and GTM in polyacrylamide gels. Furthermore, treatment of detergent-extracted G protein with endoglycosidase F and endo-alpha-N-acetylgalactosaminidase, enzymes that specifically cleave N-linked and O-linked oligosaccharides, respectively, generated a variety of partially unglycosylated species, ranging in molecular weight from approximately 80 to 40 kDa. Virus infectivity was sensitive to limited removal of N-linked or O-linked oligosaccharides by endoglycosidases under conditions which did not greatly alter the molecular weight of the G protein. Thus, G and F protein oligosaccharides readily accessible to enzymatic removal are presumed to play an important role in the infectious process.
Lambert
D M
DM
Department of Molecular Virology, James N. Gamble Institute of Medical Research, Cincinnati, Ohio 45219.
D002213:Capsid / Q000502:physiology; D004591:Electrophoresis, Polyacrylamide Gel; D006026:Glycoside Hydrolases / Q000494:pharmacology; D008562:Membrane Glycoproteins; D008970:Molecular Weight; D009439:Neuraminidase / Q000494:pharmacology; D012136:Respiratory Syncytial Viruses / Q000502:physiology*; D013329:Structure-Activity Relationship; D014415:Tunicamycin / Q000494:pharmacology; D014758:Viral Core Proteins / Q000502:physiology; D014759:Viral Envelope Proteins; D014760:Viral Fusion Proteins / Q000502:physiology*; D014763:Viral Matrix Proteins / Q000502:physiology*; D014764:Viral Proteins / Q000502:physiology*; D014779:Virus Replication
C028391:G protein, vesicular stomatitis virus; D008562:Membrane Glycoproteins; D014758:Viral Core Proteins; D014759:Viral Envelope Proteins; D014760:Viral Fusion Proteins; D014763:Viral Matrix Proteins; D014764:Viral Proteins; D014415:Tunicamycin; D006026:Glycoside Hydrolases; D009439:Neuraminidase