Parasitophorous vacuole poration precedes its rupture and rapid host erythrocyte cytoskeleton collapse in Plasmodium falciparum egress
Parasitophorous vacuole poration precedes its rupture and rapid host erythrocyte cytoskeleton collapse in Plasmodium falciparum egress
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DOI：
10.1073/pnas.1619441114
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发表时间：
2017-03-28
影响因子：
11.1
通讯作者：
Saibil, Helen R.
中科院分区：
文献类型：
--
作者：
Hale, Victoria L.;Watermeyer, Jean M.;Saibil, Helen R.
在疟疾感染的无性血液阶段，裂殖子侵入红细胞并在寄生虫空泡内复制以形成子细胞，子细胞最终通过空泡和红细胞膜的连续破裂而离开（外出）。目前的模型是PKG，一种疟疾cGMP依赖性蛋白激酶，触发外出，激活疟疾蛋白酶和其他效应物。使用PKG或半胱氨酸蛋白酶的选择性抑制剂，分别抑制膜穿孔的顺序步骤，结合视频显微镜，电子断层扫描，电子能量损失谱，和软X射线断层扫描的成熟细胞内恶性疟原虫寄生虫，我们解决中间步骤出口。我们发现，寄生虫空泡膜（PVM）透化10-30分钟之前，其PKG触发分解成多层囊泡。就在PVM分解之前，宿主红细胞由于红细胞骨架的突然分解而经历突然的、戏剧性的形状变化，然后透化并最终破裂红细胞膜以释放寄生虫。与之前PKG触发的出口启动和宿主红细胞骨架在胞体发育过程中逐渐解体的观点相反，我们的研究结果确定了出口的初始步骤，并表明宿主细胞骨架分解仅限于出口最后阶段内的狭窄时间窗口。
In the asexual blood stages of malarial infection, merozoites invade erythrocytes and replicate within a parasitophorous vacuole to form daughter cells that eventually exit (egress) by sequential rupture of the vacuole and erythrocyte membranes. The current model is that PKG, a malarial cGMP-dependent protein kinase, triggers egress, activating malarial proteases and other effectors. Using selective inhibitors of either PKG or cysteine proteases to separately inhibit the sequential steps in membrane perforation, combined with video microscopy, electron tomography, electron energy loss spectroscopy, and soft X-ray tomography of mature intracellular Plasmodium falciparum parasites, we resolve intermediate steps in egress. We show that the parasitophorous vacuole membrane (PVM) is permeabilized 10-30 min before its PKG-triggered breakdown into multilayered vesicles. Just before PVM breakdown, the host red cell undergoes an abrupt, dramatic shape change due to the sudden breakdown of the erythrocyte cytoskeleton, before permeabilization and eventual rupture of the erythrocyte membrane to release the parasites. In contrast to the previous view of PKG-triggered initiation of egress and a gradual dismantling of the host erythrocyte cytoskeleton over the course of schizont development, our findings identify an initial step in egress and show that host cell cytoskeleton breakdown is restricted to a narrow time window within the final stages of egress.