Molecular Parasitology, Humboldt University, Berlin, Germany.
Centre for Advanced Microscopy, Australian National University, Canberra ACT, Australia.
PLoS Pathog. 2022 Sep 20;18(9):e1010846. doi: 10.1371/journal.ppat.1010846. eCollection 2022 Sep.
Protein export and host membrane remodeling are crucial for multiple Plasmodium species to establish a niche in infected hosts. To better understand the contribution of these processes to successful parasite infection in vivo, we sought to find and characterize protein components of the intraerythrocytic Plasmodium berghei-induced membrane structures (IBIS) that form in the cytoplasm of infected erythrocytes. We identified proteins that immunoprecipitate with IBIS1, a signature member of the IBIS in P. berghei-infected erythrocytes. In parallel, we also report our data describing proteins that co-precipitate with the PTEX (Plasmodium translocon of exported proteins) component EXP2. To validate our findings, we examined the location of three candidate IBIS1-interactors that are conserved across multiple Plasmodium species, and we found they localized to IBIS in infected red blood cells and two further colocalized with IBIS1 in the liver-stage parasitophorous vacuole membrane. Successful gene deletion revealed that these two tryptophan-rich domain-containing proteins, termed here IPIS2 and IPIS3 (for intraerythrocytic Plasmodium-induced membrane structures), are required for efficient blood-stage growth. Erythrocytes infected with IPIS2-deficient schizonts in particular fail to bind CD36 as efficiently as wild-type P. berghei-infected cells and therefore fail to effectively sequester out of the circulating blood. Our findings support the idea that intra-erythrocytic membrane compartments are required across species for alterations of the host erythrocyte that facilitate interactions of infected cells with host tissues.
蛋白输出和宿主膜重塑对于多种疟原虫在感染宿主中建立小生境至关重要。为了更好地理解这些过程对寄生虫在体内成功感染的贡献，我们试图寻找和鉴定在疟原虫内的红内期诱导膜结构（IBIS）中形成的蛋白成分，这些结构存在于受感染的红细胞细胞质中。我们鉴定了与 IBIS1 免疫沉淀的蛋白，IBIS1 是 P. berghei 感染红细胞中 IBIS 的一个特征成员。同时，我们还报告了与 PTEX（疟原虫输出蛋白转运器）成分 EXP2 共沉淀的蛋白的数据。为了验证我们的发现，我们检查了三个候选 IBIS1 相互作用蛋白的位置，这些蛋白在多种疟原虫中是保守的，我们发现它们定位于受感染的红细胞中的 IBIS 中，另外两个与 IBIS1 共定位于肝期寄生泡膜中。成功的基因缺失表明，这两个富含色氨酸的结构域蛋白，在这里称为 IPIS2 和 IPIS3（红细胞内疟原虫诱导的膜结构），对于有效的血期生长是必需的。特别是感染了 IPIS2 缺陷裂殖子的红细胞，与野生型 P. berghei 感染细胞相比，不能有效地结合 CD36，因此不能有效地将自身从循环血液中隔离出来。我们的研究结果支持这样一种观点，即在物种间，红细胞内膜隔室对于改变宿主红细胞以促进感染细胞与宿主组织的相互作用是必需的。
