Plasma membrane targeting of chimeric intracisternal A-type particle polyproteins leads to particle release and specific activation of the viral proteinase
Plasma membrane targeting of chimeric intracisternal A-type particle polyproteins leads to particle release and specific activation of the viral proteinase
复制标题
嵌合脑池内 A 型颗粒多蛋白的质膜靶向导致颗粒释放和病毒蛋白酶的特异性激活
DOI：
10.1128/jvi.71.7.5209-5217.1997
复制
发表时间：
1997
影响因子：
5.4
通讯作者：
H. Kräusslich
中科院分区：
文献类型：
--
作者：
R. Welker;Alfred Janetzko;H. Kräusslich
逆转录病毒形态发生涉及结构 Gag 多蛋白的组装，随后从质膜出芽，然后通过病毒蛋白酶 (PR) 进行蛋白水解切割，并在细胞外成熟为感染性病毒颗粒。脑池内 A 型颗粒 (IAP) 是有缺陷的逆转录病毒，在内质网 (ER) 膜上组装和出芽，它们在内质网 (ER) 膜上保持为仅由未切割的多蛋白组成的不成熟颗粒。为了分析细胞内多蛋白转运和 PR 激活的要求，我们在 IAP gag 基因中构建了缺失和替换突变，包括假定的 ER 靶向信号。突变的多蛋白被转运到细胞内的各个位置，包括细胞核、细胞质、内质网和质膜。有趣的是，几乎所有位点都发生了衣壳样颗粒结构的组装。然而，只有那些转运到质膜的多蛋白才能被病毒 PR 有效且特异性地切割，切割主要发生在病毒颗粒内。因此，至少在这里提出的实验系统中，逆转录病毒颗粒组装几乎可以发生在细胞内的任何位置，而多蛋白加工以及因此导致的病毒颗粒成熟仅限于特定的细胞位点。这些结果表明，需要一种仅限于质膜的因子来触发感染性逆转录病毒的 PR 激活和成熟。
Retrovirus morphogenesis involves assembly of structural Gag polyproteins with subsequent budding from the plasma membrane, followed by proteolytic cleavage by the viral proteinase (PR) and extracellular maturation to the infectious virion. Intracisternal A-type particles (IAPs) are defective retroviruses that assemble and bud at the membranes of the endoplasmic reticulum (ER), where they remain as immature particles consisting exclusively of uncleaved polyproteins. To analyze requirements for intracellular polyprotein transport and PR activation, we constructed deletion and substitution mutations in the IAP gag gene, including the putative ER-targeting signal. Mutant polyproteins were transported to various intracellular locations, including the nucleus, the cytoplasm, the ER, and the plasma membrane. Interestingly, assembly of capsid-like particle structures occurred at almost all sites. However, only those polyproteins transported to the plasma membrane were efficiently and specifically cleaved by viral PR, with cleavage occurring predominantly within the virus particle. Thus, at least in the experimental system presented here, retroviral particle assembly can occur at almost any location within the cell, while polyprotein processing and, consequently, virion maturation are confined to a specific cellular site. These results suggest that a factor restricted to the plasma membrane is required to trigger PR activation and maturation of infectious retroviruses.