title: Acidic amino acids increase fusion activity in the specific fusion domain of Newcastle disease virus fusion protein.
abstract: To explore the effects of amino acids Gln and Asn within the specific fusion domain of fusion (F) protein on the specific membrane fusion in Newcastle disease virus (NDV), the mutants Q204E-Q205E and N245D were constructed in the specific fusion domain of F protein. The mutant genes were co-expressed with homologous or heterologous hemagglutinin-neuraminidase (HN) in BHK21 cells. Cell fusion functions of mutants were analyzed with Giemsa staining and reporter gene methods. Cell surface expression efficiency was analyzed with immunofluorescence assay and fluorescence-activated cell sorter analysis. Co-immunoprecipitation was performed to analyze the interaction of mutant F proteins with the homotypic HN protein. Both Q204E-Q205E and N245D mutations caused increased cell-cell fusion activity when they were co-expressed with homotypic HN protein. The mutant F proteins had slight changes in cell surface expression compared with that of wild-type F protein. The interactions of Q204E-Q205E or N245D with their homotypic HN increased significantly (P < 0.01) compared with the wild-type F protein. Neither Q204-Q205E nor N245D caused cell fusion in the presence of heterologous HN protein. Our data suggested that the residues Q204, Q205, and N245 play a critical role in the regulation of cell fusion. They may decrease the interaction of wild-type NDV F and NDV HN to suppress the fusion activity for survival of the infected host, which may enable a persistent virus infection and long-term virus reproduction and spread.
authors.affiliation: a Institute of Biochemistry and Molecular Biology, School of Medicine, Shandong University, Jinan 250012, People's Republic of China.
authors.forename: Guijie
authors.initials: G
authors.lastname: Ren
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Zhuang
authors.forename: Keli
authors.initials: K
authors.lastname: Tian
authors.forename: Huiyu
authors.initials: H
authors.lastname: Li
authors.forename: Xueqin
authors.initials: X
authors.lastname: Diao
authors.forename: Miaomiao
authors.initials: M
authors.lastname: Wang
authors.forename: Nan
authors.initials: N
authors.lastname: Zhou
authors.forename: Zhiyu
authors.initials: Z
authors.lastname: Wang
mesh_terms: D000818:Animals; D001216:Asparagine / Q000737:chemistry / Q000378:metabolism*; D002460:Cell Line; D005973:Glutamine / Q000737:chemistry / Q000378:metabolism*; D015707:HN Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008561:Membrane Fusion; D009521:Newcastle Disease / Q000821:virology; D009522:Newcastle disease virus / Q000502:physiology*; D017354:Point Mutation; D014760:Viral Fusion Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D015707:HN Protein; D014760:Viral Fusion Proteins; D005973:Glutamine; D001216:Asparagine