Functional interaction of paramyxovirus glycoproteins: identification of a domain in Sendai virus HN which promotes cell fusion.
The cell fusion activity of most paramyxoviruses requires coexpression of a fusion protein (F) and a hemagglutinin-neuraminidase protein (HN) which are derived from the same virus type. To define the domain of the HN protein which interacts with the F protein in a type-specific manner a series of chimeric HN proteins between two different paramyxoviruses, Sendai virus (SN) and human parainfluenza virus type 3 (PI3), was constructed and coexpressed with the SN-F protein by using the vaccinia virus T7 RNA polymerase transient-expression system. Quantitative assays were used to evaluate cell surface expression as well as fusion-promoting activities of the chimeric HN molecules. A chimeric HN protein [SN(140)] containing 140 N-terminal amino acids derived from SN-HN and the remainder (432 amino acids) derived from PI3-HN was found to promote cell fusion with the SN-F protein. In contrast, a second chimeric HN with 137 amino acids from SN-HN at the N terminus could not promote fusion with SN-F, even though the protein was expressed on the cell surface. A construct in which the PI3-HN cytoplasmic tail and transmembrane domain were substituted for those of SN in the SN(140) chimera still maintained the ability to promote cell fusion. These results indicate that a region including only 82 amino acids in the extracellular domain, adjacent to the transmembrane domain of the SN-HN protein, is important for interaction with the SN-F protein and promotion of cell fusion.
Tanabayashi
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Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
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D000818:Animals; D002459:Cell Fusion; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology / Q000821:virology; D002522:Chlorocebus aethiops; D015870:Gene Expression; D006023:Glycoproteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000502:physiology*; D015707:HN Protein / Q000096:biosynthesis / Q000302:isolation & purification / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D010222:Parainfluenza Virus 1, Human / Q000502:physiology*; D010224:Parainfluenza Virus 3, Human / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000378:metabolism; D014760:Viral Fusion Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000502:physiology*
D006023:Glycoproteins; D015707:HN Protein; D011993:Recombinant Fusion Proteins; D014760:Viral Fusion Proteins