Controlled conformational transitions in the MVM virion expose the VP1 N-terminus and viral genome without particle disassembly
Controlled conformational transitions in the MVM virion expose the VP1 N-terminus and viral genome without particle disassembly
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DOI：
10.1006/viro.1998.9520
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发表时间：
1999-02-01
期刊：
影响因子：
3.7
通讯作者：
Tattersall, P
中科院分区：
文献类型：
--
作者：
Cotmore, SF;D'Abramo, AM;Tattersall, P
针对小鼠细小病毒的衣壳蛋白VP1和VP2的n端对应肽，制备了抗血清。绝大多数新释放的病毒颗粒无法到达142个氨基酸vp1特异性区域的表位，针对它们的血清不能直接中和病毒或耗尽感染性病毒粒子的库存。然而，短暂暴露在45摄氏度或更高的温度下，会导致完整病毒粒子群体的构象转变，而在空病毒颗粒中则不会，其中vp1特异性序列可以从外部进入。相比之下，VP2 n端在没有事先处理的情况下，在所有满的颗粒中都是抗体可达的，而不是空的颗粒。电泳迁移率转移试验（在电泳前对颗粒进行热处理和/或与抗体预孵育）证实了这种表位可及性模式，表明热诱导的构象转变产生了一种迟缓形式的病毒粒子，可以通过与vp1特异性血清孵育进行超移。发生转变的病毒粒子的比例随着温度的升高而增加，但在高达70摄氏度的所有温度下，病毒颗粒保留了结构特异性抗原决定因子并基本保持完整，没有脱落单个多肽种或亚基。然而，尽管其保护层具有明显的完整性，但在这个温度范围内，越来越多的病毒粒子可以接触到外用酶，这表明暴露VP1的构象转变可能也允许进入基因组。将颗粒加热到80摄氏度或以上，最终诱导多肽单体的分解。(C) 1999学术出版社。
Antisera were raised against peptides corresponding to the N-termini of capsid proteins VP1 and VP2 from the parvovirus minute virus of mice. Epitopes in the 142-amino-acid VP1-specific region were not accessible in the great majority of newly released viral particles, and sera directed against them failed to neutralize virus directly or deplete stocks of infectious virions. However, brief exposure to temperatures of 45 degrees C or more induced a conformational transition in a population of full virions, but not in empty viral particles, in which VP1-specific sequences became externally accessible. In contrast, the VP2 N-terminus was antibody-accessible in all full, but not empty, particles without prior treatment. An electrophoretic mobility shift assay, in which particles were heat-treated and/or preincubated with antibodies prior to electrophoresis, confirmed this pattern of epitope accessibility, showing that the heat-induced conformational transition produces a retarded form of virion that can be supershifted by incubation with VP1-specific sera. The proportion of virions undergoing transition increased with temperature, but at all temperatures up to 70 degrees C viral particles retained structure-specific antigenic determinants and remained essentially intact, without shedding individual polypeptide species or subunits. However, despite the apparent integrity of its protective coat, the genome became accessible to externally applied enzymes in an increasing proportion of virions through this temperature range, suggesting that the conformational transitions that expose VP1 likely also allow access to the genome. Heating particles to 80 degrees C or above finally induced disassembly to polypeptide monomers. (C) 1999 Academic Press.