Multiple heparin binding domains of respiratory syncytial virus G mediate binding to mammalian cells.
Respiratory syncytial virus (RSV) G glycoprotein mediates cell attachment through surface glycosaminoglycans (GAGs). Feldman et al. [10] suggested that specific basic amino acids in residues 184-198 of G defined a critical heparin binding domain (HBD). To further define the G HBD we made a series of truncated G proteins expressed in Escherichia coli. G88 (G residues 143-231), bound to HEp-2 cells in a dose dependent manner and binding was inhibited >99% with heparin. Cell binding of G88 was unaltered by alanine substitution mutagenesis of all basic amino acids in Feldman's region 184-198. A G88 variant truncated beyond residue 198, G58, and G58 fully alanine substituted in the region 184-198, G58A6, bound to HEp-2 cells about half as well and 100-fold less well than G88, respectively. G88 and all alanine substitution mutants of G88 inhibited RSV plaque formation by 50% (ID(50)) at concentrations of approximately 50 nM; the ID(50) of G58 was approximately 425 nM while G58A6 had an ID(50) >1600 nM. These data show that the G HBD includes as much as residues 187-231, that there is redundancy beyond the previously described HBD, and that the cell-binding and virus infectivity-blocking functions of these recombinant G proteins were closely linked and required at least one HBD.
Shields
B
B
Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Australia.
Mills
J
J
Ghildyal
R
R
Gooley
P
P
Meanger
J
J
D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D015967:Gene Expression Regulation, Viral; D006493:Heparin / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D011994:Recombinant Proteins / Q000378:metabolism; D012136:Respiratory Syncytial Viruses / Q000378:metabolism* / Q000472:pathogenicity; D016415:Sequence Alignment; D014407:Tumor Cells, Cultured; D010948:Viral Plaque Assay; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D011994:Recombinant Proteins; D014764:Viral Proteins; D006493:Heparin