Antiviral activity and structural characteristics of the nonglycosylated central subdomain of human respiratory syncytial virus attachment (G) glycoprotein.
Segments of the cystine noose-containing nonglycosylated central subdomain, residues 149-197, of the attachment (G) glycoprotein of human respiratory syncytial virus (HRSV) have been assessed for impact on the cytopathic effect (CPE) of respiratory syncytial virus (RSV). Nalpha-acetyl residues 149-197-amide (G149-197), G149-189, and G149-177 of the A2 strain of HRSV protected 50% of human epithelial HEp-2 cells from the CPE of the A2 strain at concentrations (IC(50)) between 5 and 80 microm. Cystine noose-containing peptides G171-197 and G173-197 did not inhibit the CPE even at concentrations above 150 microm. Systematic C- and N-terminal truncations from G149-189 and G149-177 and alanine substitutions within G154-177 demonstrated that residues 166-170 (EVFNF), within a sequence that is conserved in HRSV strains, were critical for inhibition. Concordantly, G154-177 of bovine RSV and of an antibody escape mutant of HRSV with residues 166-170 of QTLPY and EVSNP, respectively, were not inhibitory. Surprisingly, a variant of G154-177 with an E166A substitution had an IC(50) of 750 nm. NMR analysis demonstrated that G149-177 adopted a well-defined conformation in solution, clustered around F168 and F170. G154-170, particularly EVFNF, may be important in binding of RSV to host cells. These findings constitute a promising platform for the development of antiviral agents for RSV.
Gorman
J J
JJ
Biomolecular Research Institute, 343 Royal Parade, Parkville, Victoria 3052, Australia. jeff.gorman@hsn.csiro.au
McKimm-Breschkin
J L
JL
Norton
R S
RS
Barnham
K J
KJ
D000409:Alanine / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002417:Cattle; D006031:Glycosylation; D006801:Humans; D020128:Inhibitory Concentration 50; D009682:Magnetic Resonance Spectroscopy; D008562:Membrane Glycoproteins / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D018113:Respiratory Syncytial Virus, Human / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid; D012756:Sheep; D014759:Viral Envelope Proteins / Q000737:chemistry*
D000998:Antiviral Agents; C066028:G protein, Bovine respiratory syncytial virus; D008562:Membrane Glycoproteins; D010455:Peptides; D014759:Viral Envelope Proteins; C439064:glycoprotein O, Human respiratory syncytial virus; D000409:Alanine