title: N-linked glycan at residue 523 of human parainfluenza virus type 3 hemagglutinin-neuraminidase masks a second receptor-binding site.
abstract: The hemagglutinin-neuraminidase (HN) glycoprotein plays a critical role in parainfluenza virus replication. We recently found that in addition to the catalytic binding site, HN of human parainfluenza virus type 1 (hPIV-1) may have a second receptor-binding site covered by an N-linked glycan at residue 173, which is near the region of the second receptor-binding site identified in Newcastle disease virus (NDV) HN (I. A. Alymova, G. Taylor, V. P. Mishin, M. Watanabe, K. G. Murti, K. Boyd, P. Chand, Y. S. Babu, and A. Portner, J. Virol. 82:8400-8410, 2008). Sequence analysis and superposition of the NDV and hPIV-3 HN dimer structures revealed that, similar to what was seen in hPIV-1, the N-linked glycan at residue 523 on hPIV-3 HN may cover a second receptor-binding site. Removal of this N-linked glycosylation site by an Asn-to-Asp substitution at residue 523 (N523D) changed the spectrum of the mutant virus's receptor specificity, delayed its elution from both turkey and chicken red blood cells, reduced mutant sensitivity (by about half) to the selective HN inhibitor BCX 2855 in hemagglutination inhibition tests, and slowed its growth in LLC-MK(2) cells. The neuraminidase activity of the mutant and its sensitivity to BCX 2855 in neuraminidase inhibition assays did not change, indicating that the mutation did not affect the virus's catalytic-binding site and that all observed effects were caused by the exposure of the purported second receptor-binding site. Our data are consistent with the idea that, similar to the case for hPIV-1, the N-linked glycan shields a second receptor-binding site on hPIV-3 HN.
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, Tennessee 38105-3678, USA.
authors.forename: Vasiliy P
authors.initials: VP
authors.lastname: Mishin
authors.forename: Makiko
authors.initials: M
authors.lastname: Watanabe
authors.forename: Garry
authors.initials: G
authors.lastname: Taylor
authors.forename: John
authors.initials: J
authors.lastname: Devincenzo
authors.forename: Michael
authors.initials: M
authors.lastname: Bose
authors.forename: Allen
authors.initials: A
authors.lastname: Portner
authors.forename: Irina V
authors.initials: IV
authors.lastname: Alymova
mesh_terms: D000818:Animals; D001665:Binding Sites; D002645:Chickens; D006031:Glycosylation; D015707:HN Protein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D009439:Neuraminidase / Q000378:metabolism; D010222:Parainfluenza Virus 1, Human / Q000378:metabolism; D010224:Parainfluenza Virus 3, Human / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011134:Polysaccharides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D014422:Turkeys; D014779:Virus Replication
chemical_list: D015707:HN Protein; D011134:Polysaccharides; D009439:Neuraminidase