THE PARASITOPHOROUS VACUOLE MEMBRANE SURROUNDING INTRACELLULAR TOXOPLASMA-GONDII FUNCTIONS AS A MOLECULAR-SIEVE
THE PARASITOPHOROUS VACUOLE MEMBRANE SURROUNDING INTRACELLULAR TOXOPLASMA-GONDII FUNCTIONS AS A MOLECULAR-SIEVE
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DOI：
10.1073/pnas.91.2.509
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发表时间：
1994-01-18
影响因子：
11.1
通讯作者：
JOINER, KA
中科院分区：
文献类型：
--
作者：
SCHWAB, JC;BECKERS, CJM;JOINER, KA
专性细胞内原生动物弓形虫在入侵哺乳动物宿主细胞时，会产生并进入一个独特的膜结合的细胞质隔室--寄生虫液泡。通过向单个弓形虫感染的成纤维细胞微量注射极性荧光分子，我们在这里证明了围绕着寄生虫的寄生液泡膜(PVM)起着分子筛子的作用。荧光黄(457Da)显示出跨越PVM的自由双向流动，并清楚地勾勒出液泡内没有吸收染料的寄生虫。用5 mM丙磺舒对细胞进行预处理或将单层冷却到5摄氏度并没有明显延迟染料的移动，这表明染料移动是由于被动渗透通过膜孔而不是主动运输。钙黄绿素、Fluo-3和一系列长达1291 Da的荧光素异硫氰酸酯标记的多肽以大小受限的方式穿过PVM。1926Da的标记肽和标记的右旋糖苷和蛋白质(大于或等于3000Da)不能通过PVM。因此，PVM中的这一可能的通道允许寄主细胞质和寄生液泡空间之间高达1300-1900 Da的分子交换。
The obligate intracellular protozoan parasite Toxoplasma gondii creates and enters into a unique membrane-bounded cytoplasmic compartment, the parasitophorous vacuole, when invading mammalian host cells. By microinjecting polar fluorescent molecules into individual T. gondii-infected fibroblasts, we show here that the parasitophorous vacuole membrane (PVM) surrounding the parasite functions as a molecular sieve. Lucifer yellow (457 Da) displayed free bidirectional flux across the PVM and distinctly outlined the parasites, which did not take up the dye, within the vacuole. This dye movement was not appreciably delayed by pretreatment of cells with 5 mM probenecid or chilling the monolayer to 5 degrees C, suggesting that dye movement was due to passive permeation through a membrane pore rather than active transport. Calcein, fluo-3, and a series of fluorescein isothio-cyanate-labeled peptides up to 1291 Da crossed the PVM in a size-restricted fashion. A labeled peptide of 1926 Da and labeled dextrans and proteins (greater than or equal to 3000 Da) failed to transit the PVM. This putative channel in the PVM therefore allows exchange of molecules up to 1300-1900 Da between the host cell cytoplasm and the parasitophorous vacuolar space.