Decreased dependence on receptor recognition for the fusion promotion activity of L289A-mutated Newcastle disease virus fusion protein correlates with a monoclonal antibody-detected conformational change
Decreased dependence on receptor recognition for the fusion promotion activity of L289A-mutated Newcastle disease virus fusion protein correlates with a monoclonal antibody-detected conformational change
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DOI：
10.1128/jvi.79.2.1180-1190.2005
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发表时间：
2005-01-01
影响因子：
5.4
通讯作者：
Iorio, RM
中科院分区：
文献类型：
--
作者：
Li, JR;Melanson, VR;Iorio, RM
研究表明，L289A突变的新城疫病毒(NDV)融合蛋白(F)具有独立于病毒血凝素神经氨酸酶(HN)蛋白促进Cos-7细胞融合的能力，并且与野生型(Wt)F蛋白相比，HN依赖融合蛋白的融合能力提高了50%。在这里，我们证明了L289A-F的HN非依赖性融合在BHK细胞或其他几种细胞系中没有表现出来。然而，与Cos-7细胞的结果相似，突变蛋白加HN在所有测试的细胞系中确实比wt水平多促进50%至70%的融合。L289A-F蛋白对同源HN蛋白以及新城疫病毒-人副流感病毒3HN嵌合体具有与wt F蛋白相同的特异性。当突变的F蛋白与缺乏受体识别活性的嵌合体或HN蛋白共表达时，它比wt蛋白更有效地促进融合。此外，它的融合活性明显更能抵抗靶细胞上唾液酸的去除。这些发现与细胞表面免疫共沉淀实验证明L289A-F比wt F更有效地与wt和突变的HN蛋白相互作用是一致的。综上所述，这些发现表明，L289A-F促进融合的机制类似于wt蛋白的HN-F相互作用，但对HN的附着活性依赖较少。突变的F蛋白的表型与两种不同的单抗可检测到的蛋白的构象变化相关。这种构象变化可能反映了L289A替代引起的F结构的不稳定，这反过来可能表明融合激活所需的能量较低。
It has been shown that the L289A-mutated Newcastle disease virus (NDV) fusion (F) protein gains the ability to promote fusion of Cos-7 cells independent of the viral hemagglutinin-neuraminidase (HN) protein and exhibits a 50% enhancement in HN-dependent fusion over wild-type (wt) F protein. Here, we show that HN-independent fusion by L289A-F is not exhibited in BHK cells or in several other cell lines. However, similar to the results in Cos-7 cells, the mutated protein plus HN does promote 50 to 70% more fusion above wt levels in all of the cell lines tested. L289A-F protein exhibits the same specificity as the wt F protein for the homologous HN protein, as well as NDV-human parainfluenza virus 3 HN chimeras. The mutated F protein promotes fusion more effectively than the wt when it is coexpressed with either the chimeras or HN proteins deficient in receptor recognition activity. In addition, its fusogenic activity is significantly more resistant to removal of sialic acid on target cells. These findings are consistent with the demonstration that L289A-F interacts more efficiently with wt and mutated HN proteins than does wt F by a cell surface coimmunoprecipitation assay. Taken together, these findings indicate that L289A-F promotes fusion by a mechanism analogous to that of the wt protein with respect to the HN-F interaction but is less dependent on the attachment activity of HN. The phenotype of the mutated F protein correlates with a conformational change in the protein detectable by two different monoclonal antibodies. This conformational change may reflect a destabilization of F structure induced by the L289A substitution, which may in turn indicate a lower energy requirement for fusion activation.