Effects of multiple amino acids of the parainfluenza virus 5 fusion protein on its haemagglutinin-neuraminidase-independent fusion activity
Effects of multiple amino acids of the parainfluenza virus 5 fusion protein on its haemagglutinin-neuraminidase-independent fusion activity
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DOI：
10.1099/vir.0.006437-0
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发表时间：
2009-02-01
影响因子：
3.8
通讯作者：
Tsurudome, Masato
中科院分区：
文献类型：
--
作者：
Ito, Morihiro;Nishio, Machiko;Tsurudome, Masato
副流感病毒5（PIV-5）株W3A的融合(F)蛋白在幼鼠肾细胞中单独表达时能够诱导细胞融合，而PIV-5株WR的F蛋白只有在与血凝素-神经氨酸酶（FIN）蛋白共表达时才能诱导细胞融合。先前的研究表明，当WR F蛋白的Leu-22被W3A F对应蛋白（Pro-22）取代时，产生的突变体L22P表现出不依赖于hn的融合活性。此外，先前对PIV-5菌株T1的L22P与F蛋白的嵌合分析表明，Glu-132也参与了L22P不依赖于fin的融合活性。结果表明，L22P的Glu-132被包括T1 F蛋白对应物（Lys-132）在内的各种氨基酸取代导致融合活性降低，而与Asp取代则是耐受的例外。有趣的是，含有E132K取代的L22P突变体的融合活性降低可以通过额外的D416K取代来恢复，但不能通过D416E突变来恢复，这表明在132和416位置存在相同的电荷对于不依赖hn的融合活性很重要。相反，将WR F蛋白的Leu-22替换为除脂肪侧链外的各种氨基酸，可以获得融合活性，这表明WR F蛋白在诱导细胞融合时依赖于FIN是由于Leu-22的疏水性。这些结果表明，至少有三个氨基酸参与了piv - 5f蛋白不依赖于hn的融合活性。
The fusion (F) protein of parainfluenza virus 5(PIV-5) strain W3A is able to induce cell fusion when it is expressed alone in baby hamster kidney cells, whilst the F protein of PIV-5 strain WR induces cell fusion only when co-expressed with the haemagglutinin-neuraminidase (FIN) protein. It has been shown previously that when Leu-22 of the WR F protein is replaced with the W3A F counterpart (Pro-22), the resulting mutant L22P exhibits HN-independent fusion activity. Furthermore, previous chimeric analysis between L22P and the F protein of PIV-5 strain T1 has suggested that Glu-132 also contributes to the FIN-independent fusion activity of L22P. It was shown here that substitution of Glu-132 of L22P with various amino acids including the T1 F protein counterpart (Lys-132) resulted in a reduction in fusion activity, whereas substitution with Asp was the exception in being tolerated. Interestingly, reduced fusion activity of an L22P mutant that harboured the E132K substitution could be restored by an additional D416K substitution but not by a D416E mutation, suggesting that the presence of the same charge at positions 132 and 416 is important for the HN-independent fusion activity. In contrast, substitution of Leu-22 of the WR F protein with various amino acids except those with aliphatic side chains resulted in acquisition of fusion activity, suggesting that the FIN dependence of the WR F protein in the induction of cell fusion is attributable to the hydrophobicity of Leu-22. These results indicate that at least three amino acids are involved in the HN-independent fusion activity of the PIV-5 F protein.