Minns Allen M, Hart Kevin J, Subramanian Suriyasri, Hafenstein Susan, Lindner Scott E
Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, USA.
Center for Malaria Research, Pennsylvania State University, University Park, Pennsylvania, USA.
mSphere. 2018 Jan 10;3(1). doi: 10.1128/mSphere.00435-17. eCollection 2018 Jan-Feb.
Malaria is a devastating illness that causes approximately 500,000 deaths annually. The malaria-causing parasite ( genus) uses the process of translational repression to regulate its growth, development, and transmission. As poly(A)-binding proteins (PABP) have been identified as critical components of RNA metabolism and translational repression in model eukaryotes and in , we have identified and investigated two PABPs in , PyPABP1 and PyPABP2. In contrast to most single-celled eukaryotes, closely resembles metazoans and encodes both a nuclear PABP and a cytosolic PABP; here, we provide multiple lines of evidence in support of this observation. The conserved domain architectures of PyPABP1 and PyPABP2 resemble those of yeast and metazoans, while multiple independent binding assays demonstrated their ability to bind very strongly and specifically to poly(A) sequences. Interestingly, we also observed that purified PyPABP1 forms homopolymeric chains despite exhaustive RNase treatment . Finally, we show by indirect immunofluorescence assays (IFAs) that PyPABP1 and PyPABP2 are cytoplasm- and nucleus-associated PABPs during the blood stages of the life cycle. Surprisingly, however, PyPABP1 was instead observed to also be localized on the surface of transmitted salivary gland sporozoites and to be deposited in trails when parasites glide on a substrate. This is the third RNA-binding protein verified to be found on the sporozoite surface, and the data may point to an unappreciated RNA-centered interface between the host and parasite. Malaria remains one of the great global health problems. The parasite that causes malaria ( genus) relies upon exquisite control of its transmission between vertebrate hosts and mosquitoes. One crucial way that it does so is by proactively producing mRNAs needed to establish the new infection but by silencing and storing them until they are needed. One key protein in this process of translational repression in model eukaryotes is poly(A)-binding protein (PABP). Here we have shown that utilizes both a nuclear PABP and a cytosolic PABP, both of which bind specifically to polyadenylated RNA sequences. Moreover, we find that the cytosolic PABP forms chains , consistent with its appreciated role in coating the poly(A) tails of mRNA. Finally, we have also verified that, surprisingly, the cytosolic PABP is found on the surface of sporozoites. Taking the data together, we propose that utilizes a more metazoan-like strategy for RNA metabolism using specialized PABPs.
疟疾是一种毁灭性疾病，每年导致约50万人死亡。引起疟疾的寄生虫（属）利用翻译抑制过程来调节其生长、发育和传播。由于聚腺苷酸结合蛋白（PABP）已被确定为模式真核生物和中的RNA代谢和翻译抑制的关键成分，我们在中鉴定并研究了两种PABP，即PyPABP1和PyPABP2。与大多数单细胞真核生物不同，与后生动物非常相似，编码一种核PABP和一种胞质PABP；在这里，我们提供了多条证据支持这一观察结果。PyPABP1和PyPABP2的保守结构域结构类似于酵母和后生动物，而多项独立结合试验证明它们能够非常强烈且特异性地结合聚腺苷酸序列。有趣的是，我们还观察到，尽管经过了彻底的核糖核酸酶处理，纯化的PyPABP1仍形成同聚物链。最后，我们通过间接免疫荧光试验（IFA）表明，在生命周期的血液阶段，PyPABP1和PyPABP2是与细胞质和细胞核相关的PABP。然而，令人惊讶的是，相反观察到PyPABP1也定位在传播的唾液腺子孢子表面，并且当寄生虫在底物上滑行时沉积在痕迹中。这是第三种被证实存在于子孢子表面的RNA结合蛋白，这些数据可能指向宿主与寄生虫之间未被重视的以RNA为中心的界面。疟疾仍然是全球重大的健康问题之一。引起疟疾的寄生虫（属）依赖于对其在脊椎动物宿主和蚊子之间传播的精确控制。它这样做的一个关键方式是主动产生建立新感染所需的mRNA，但通过沉默和储存它们直到需要时。在模式真核生物的这种翻译抑制过程中的一种关键蛋白质是聚腺苷酸结合蛋白（PABP）。在这里我们表明利用了一种核PABP和一种胞质PABP，两者都特异性地结合聚腺苷酸化的RNA序列。此外，我们发现胞质PABP形成链，这与其在包被mRNA的聚腺苷酸尾巴方面的已知作用一致。最后，我们还证实，令人惊讶的是，胞质PABP存在于子孢子表面。综合这些数据，我们提出利用一种更类似于后生动物的策略，使用专门的PABP进行RNA代谢。
