title: A single amino acid substitution modulates low-pH-triggered membrane fusion of GP64 protein in Autographa californica and Bombyx mori nucleopolyhedroviruses.
abstract: We have previously shown that budded viruses of Bombyx mori nucleopolyhedrovirus (BmNPV) enter the cell cytoplasm but do not migrate into the nuclei of non-permissive Sf9 cells that support a high titer of Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) multiplication. Here we show, using the syncytium formation assay, that low-pH-triggered membrane fusion of BmNPV GP64 protein (Bm-GP64) is significantly lower than that of AcMNPV GP64 protein (Ac-GP64). Mutational analyses of GP64 proteins revealed that a single amino acid substitution between Ac-GP64 H155 and Bm-GP64 Y153 can have significant positive or negative effects on membrane fusion activity. Studies using bacmid-based GP64 recombinant AcMNPV harboring point-mutated ac-gp64 and bm-gp64 genes showed that Ac-GP64 H155Y and Bm-GP64 Y153H substitutions decreased and increased, respectively, the multiplication and cell-to-cell spread of progeny viruses. These results indicate that Ac-GP64 H155 facilitates the low-pH-triggered membrane fusion reaction between virus envelopes and endosomal membranes.
authors.affiliation: Laboratory of Biodynamics, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Katou
authors.forename: Hayato
authors.initials: H
authors.lastname: Yamada
authors.forename: Motoko
authors.initials: M
authors.lastname: Ikeda
authors.forename: Michihiro
authors.initials: M
authors.lastname: Kobayashi
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000643:Ammonium Chloride; D000818:Animals; D002460:Cell Line; D015967:Gene Expression Regulation, Viral; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009036:Moths; D017924:Nucleopolyhedroviruses / Q000235:genetics*; D011994:Recombinant Proteins; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism*; D053586:Virus Internalization
chemical_list: D011994:Recombinant Proteins; D014764:Viral Proteins; D000643:Ammonium Chloride