Wang Zhiyu, Mirza Anne M, Li Jianrong, Mahon Paul J, Iorio Ronald M
Department of Molecular Genetics and Microbiology, University of Massachusetts, 55 Lake Avenue North, 0165-0122, Worcester, MA, USA.
Virus Res. 2004 Feb;99(2):177-85. doi: 10.1016/j.virusres.2003.11.010.
The promotion of membrane fusion by the fusion (F) protein of human parainfluenza virus 3 (hPIV3) is dependent on a virus-specific contribution from the hemagglutinin-neuraminidase (HN) protein. By evaluation of chimeric hPIV3-Newcastle disease virus (NDV) HN proteins, we have previously shown that hPIV3-F-specificity is determined by a domain that extends from the middle of the membrane anchor to the 82nd residue in the ectodomain [Virology 209, (1995) 457; Arch. Virol. 13 (1997) 115]. If the corresponding NDV-derived residues replace the two C-terminal residues in this domain, no fusion is detected. However, these substitutions restore a glycosylation site present in NDV HN, but not in hPIV3 HN. Deletion of this site from a nested set of chimeras with hPIV3-derived N-terminal portions of decreasing length partially restores fusion, suggesting that an oligosaccharide near the top of hPIV3 HN stalk modulates fusion. In addition, further mutational analyses show that a chimera with only 125 N-terminal hPIV3-derived residues (72 in the stalk) actually promotes fusion more efficiently than the wt protein. These findings localize the C-terminus of the F-specific domain in hPIV3 HN a full 10 residues closer to the membrane than previously shown.
人副流感病毒3型（hPIV3）的融合（F）蛋白对膜融合的促进作用依赖于血凝素神经氨酸酶（HN）蛋白的病毒特异性贡献。通过对嵌合的hPIV3-新城疫病毒（NDV）HN蛋白进行评估，我们先前已表明hPIV3-F特异性由一个结构域决定，该结构域从膜锚定区中部延伸至胞外区第82个残基[《病毒学》209, (1995) 457；《病毒学杂志》13 (1997) 115]。如果该结构域中相应的源自NDV的残基取代这两个C末端残基，则检测不到融合。然而，这些取代恢复了NDV HN中存在但hPIV3 HN中不存在的一个糖基化位点。从一系列嵌套的嵌合体中删除该位点，这些嵌合体具有长度逐渐减小的源自hPIV3的N末端部分，部分恢复了融合，这表明hPIV3 HN柄顶部附近的一个寡糖调节融合。此外，进一步的突变分析表明，一个仅具有125个源自hPIV3的N末端残基（柄中有72个）的嵌合体实际上比野生型蛋白更有效地促进融合。这些发现将hPIV3 HN中F特异性结构域的C末端定位到比先前所示更靠近膜整整10个残基的位置。
