title: Identification of domains on the fusion (F) protein trimer that influence the hemagglutinin-neuraminidase specificity of the f protein in mediating cell-cell fusion.
abstract: For most paramyxoviruses, virus type-specific interaction between fusion (F) protein and attachment protein (hemagglutinin-neuraminidase [HN], hemagglutinin [H], or glycoprotein [G]) is a prerequisite for mediating virus-cell fusion and cell-cell fusion. Our previous cell-cell fusion assay using the chimeric F proteins of human parainfluenza virus 2 (HPIV2) and simian virus 41 (SV41) suggested that the middle region of the HPIV2 F protein contains the site(s) that determines its specificity for the HPIV2 HN protein. In the present study, we further investigated the sites of the F protein that could be critical for determining the HN protein specificity. By analyzing the reported structure of the F protein of parainfluenza virus 5 (PIV5), we found that four major domains (M1, M2, M3, and M4) and five minor domains (A to E) in the middle region of the PIV5 F protein were exposed on the trimer surface. We then replaced these domains with the SV41 F counterparts individually or in combination and examined whether the resulting chimeras could mediate cell-cell fusion when coexpressed with the SV41 HN protein. The results showed that a chimera designated M(1+2), which harbored SV41 F-derived domains M1 and M2, mediated cell-cell fusion with the coexpressed SV41 HN protein, suggesting that these domains are involved in determining the HN protein specificity. Intriguingly, another chimera which harbored the SV41 F-derived domain B in addition to domains M1 and M2 showed increased specificity for the SV41 HN protein compared to that of M(1+2), although it was capable of mediating cell-cell fusion by itself.
authors.affiliation: Department of Microbiology and Molecular Genetics, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan. turudome@doc.medic.mie-u.ac.jp
authors.forename: Masato
authors.initials: M
authors.lastname: Tsurudome
authors.forename: Morihiro
authors.initials: M
authors.lastname: Ito
authors.forename: Machiko
authors.initials: M
authors.lastname: Nishio
authors.forename: Mito
authors.initials: M
authors.lastname: Nakahashi
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Kawano
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Komada
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Nosaka
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Ito
mesh_terms: D002459:Cell Fusion; D015707:HN Protein / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D010252:Paramyxoviridae / Q000472:pathogenicity*; D025941:Protein Interaction Mapping; D011995:Recombination, Genetic; D014760:Viral Fusion Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D015707:HN Protein; D050505:Mutant Proteins; D014760:Viral Fusion Proteins