Carbohydrate modifications of the NDV fusion protein heptad repeat domains influence maturation and fusion activity
UMass Chan Affiliations
Department of Molecular Genetics and MicrobiologyDocument Type
Journal ArticlePublication Date
2001-05-05Keywords
Animals; Blotting, Western; COS Cells; Centrifugation, Density Gradient; Cercopithecus aethiops; Fluorescent Antibody Technique; Glycosylation; Membrane Fusion; Mutation; Newcastle disease virus; Oligosaccharides; Transfection; Viral Fusion ProteinsLife Sciences
Medicine and Health Sciences
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Show full item recordAbstract
The amino acid sequence of the fusion protein (F) of Newcastle disease virus (NDV) has six potential N-linked glycosylation addition sites, five in the ectodomain (at amino acids 85, 191, 366, 447, and 471) and one in the cytoplasmic domain at amino acid 542. Two of these sites, at positions 191 and 471, are within heptad repeat (HR) domains implicated in fusion activity of the protein. To determine glycosylation site usage as well as the function of added carbohydrate, each site was mutated by substituting alanine for the serine or threonine in the addition signal. The sizes of the resulting mutant proteins, expressed in Cos cells, showed that sites at amino acids 85, 191, 366, and 471 are used. This conclusion was verified by comparing sizes of mutant proteins missing all four used sites with that of unglycosylated F protein. The role of each added oligosaccharide in the structure and function of the F protein was determined by characterizing stability, proteolytic cleavage, surface expression, and fusion activity of the mutant proteins. Elimination of the site in F(2) at amino acid 85 had the most detrimental effect, decreasing cleavage, stability, and surface expression as well as fusion activity. The protein missing the site at 191, at the carboxyl terminus of the HR1 domain, also showed modestly reduced surface expression and negligible fusion activity. Proteins missing sites at 366 and 471 (within HR2) were expressed at nearly wild-type levels but had decreased fusion activity. These results suggest that all carbohydrate side chains, individually, influence the folding or activity of the NDV F protein. Importantly, carbohydrate modifications of the HR domains impact fusion activity of the protein.Source
Virology. 2001 May 10;283(2):332-42. Link to article on publisher's siteDOI
10.1006/viro.2001.0899Permanent Link to this Item
http://hdl.handle.net/20.500.14038/34172PubMed ID
11336558Related Resources
Link to article in PubMedae974a485f413a2113503eed53cd6c53
10.1006/viro.2001.0899