The quality control and export of mRNA by RNA-binding proteins are necessary for the survival of malaria parasites, which have complex life cycles. Nuclear poly(A) binding protein 2 (NAB2), THO complex subunit 4 (THO4), nucleolar protein 3 (NPL3), G-strand binding protein 2 (GBP2) and serine/arginine-rich splicing factor 1 (SR1) are involved in nuclear mRNA export in malaria parasites. However, their roles in asexual and sexual development, and in cellular localization, are not fully understood. In this study using the rodent malaria parasite, Plasmodium berghei, we found that NAB2 and SR1, but not THO4, NPL3 or GBP2, played essential roles in the asexual development of malaria parasites. By contrast, GBP2 but not NPL3 was involved in male and female gametocyte production. THO4 was involved in female gametocyte production, but had a lower impact than GBP2. In this study, we focused on GBP2 and NAB2, which play important roles in the sexual and asexual development of malaria parasites, respectively, and examined their cellular localization. GBP2 localized to both the nucleus and cytoplasm of malaria parasites. Using immunoprecipitation coupled to mass spectrometry (IP-MS), GBP2 interacted with the proteins ALBA4, DOZI, and CITH, which play roles in translational repression. IP-MS also revealed that phosphorylated adapter RNA export protein (PHAX) domain-containing protein, an adaptor protein for exportin-1, also interacted with GBP2, implying that mRNA export occurs via the PHAX domain-containing protein pathway in malaria parasites. Live-cell fluorescence imaging revealed that NAB2 localized at the nuclear periphery. Moreover, IP-MS indicated that NAB2 interacted with transportin. RNA immunoprecipitation coupled to RNA sequencing revealed that NAB2 bound directly to 143 mRNAs, including those encoding 40S and 60S ribosomal proteins. Our findings imply that malaria parasites use an evolutionarily ancient mechanism conserved throughout eukaryotic evolution.

RNA 结合蛋白对 mRNA 的质量控制和输出对于具有复杂生命周期的疟原虫的生存是必要的。涉及核聚 (A) 结合蛋白 2 (NAB2)、THO 复合亚基 4 (THO4)、核仁蛋白 3 (NPL3)、G 链结合蛋白 2 (GBP2) 和富含丝氨酸/精氨酸的剪接因子 1 (SR1)在疟原虫的核 mRNA 输出中。然而，它们在无性和有性发育以及细胞定位中的作用尚不完全清楚。在这项使用啮齿动物疟疾寄生虫的研究中，伯氏疟原虫，我们发现 NAB2 和 SR1，但不是 THO4、NPL3 或 GBP2，在疟原虫的无性发育中起重要作用。相比之下，GBP2 而不是 NPL3 参与雄性和雌性配子体的产生。THO4 参与雌性配子体的产生，但影响低于 GBP2。在这项研究中，我们专注于 GBP2 和 NAB2，它们分别在疟原虫的有性和无性发育中起重要作用，并检查了它们的细胞定位。GBP2 定位于疟原虫的细胞核和细胞质。使用与质谱联用的免疫沉淀 (IP-MS)，GBP2 与在翻译抑制中发挥作用的蛋白质 ALBA4、DOZI 和 CITH 相互作用。IP-MS 还揭示了含有磷酸化接头 RNA 输出蛋白 (PHAX) 结构域的蛋白，通过疟原虫中含有 PHAX 结构域的蛋白质途径。活细胞荧光成像显示 NAB2 位于核外围。此外，IP-MS 表明 NAB2 与转运蛋白相互作用。RNA 免疫沉淀与 RNA 测序结合显示 NAB2 直接与 143 种 mRNA 结合，包括编码 40S 和 60S 核糖体蛋白的那些。我们的研究结果表明，疟原虫使用一种在真核生物进化过程中保守的进化上古老的机制。