KINETICS OF ENDOSOME ACIDIFICATION DETECTED BY MUTANT AND WILD-TYPE SEMLIKI FOREST VIRUS
KINETICS OF ENDOSOME ACIDIFICATION DETECTED BY MUTANT AND WILD-TYPE SEMLIKI FOREST VIRUS
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DOI：
10.1002/j.1460-2075.1986.tb04616.x
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发表时间：
1986-12-01
期刊：
影响因子：
11.4
通讯作者：
HELENIUS, A
中科院分区：
文献类型：
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作者：
KIELIAN, MC;MARSH, M;HELENIUS, A
利用塞姆利基森林病毒(SFV)及其突变体的融合特性，跟踪BHK-21细胞摄取病毒过程中的酸化动力学。以往的研究表明，胞内空泡的低pH值触发了SFV刺突糖蛋白的构象变化，激活了膜融合，启动了病毒感染。这种构象变化发生在内体中，并遵循与细胞内融合反应相同的时间过程，表明病毒暴露于内体酸性后，融合发生得很快。用野生型(Wt)SFV和具有较低融合pH阈值的SVF突变体FUS-1监测内体酸化动力学。结果表明，wt和突变病毒内化的t1/2为10min，内体酸化到wt阈值的pH为6.2，t1/2为15min。相反，内涵体pH达到了fUS-1的阈值5.3，t1/2长得多，为45min。溶酶体中SVF随后降解的t1/2为90min。研究发现，病毒最初从质膜上摄取后，通过内吞途径转运，暴露在内体酸性环境中，最终输送到溶酶体，这三个过程是明显不同步的。
The fusogenic properties of Semliki Forest virus (SFV) and its mutants were used to follow the kinetics of acidification during the endocytic uptake of virus by BHK-21 cells. It has previously been shown that the low pH of endocytic vacuoles triggers a conformational change in the SFV spike glycoprotein, activating membrane fusion and initiating virus infection. This conformational alteration was here shown to occur in endosomes and to follow the same time course as the intracellular fusion reaction, demonstrating that fusion occurs rapidly after virus exposure to endosome acidity. The kinetics of endosome acidification were monitored using wild type (wt) SFV and fus-1, an SVF mutant with a lower fusion pH threshold. The results presented here demonstrated that wt and mutant virus were internalized with a t1/2 of 10 min, and that endosomes were acidified to the wt threshold of pH 6.2 with a t1/2 of 15 min. In contrast, endosome pH reached the fus-1 threshold of 5.3 with a much longer t1/2 of 45 min. The subsequent degradation of SVF in lysosomes had a t1/2 of 90 min. It was found that after the initial uptake of virus from the plasma membrane, its transit through the endocytic pathway, exposure to endosome acidity and eventual delivery to lysosomes were markedly asynchronous.