Yang Chunlin, Doud Emma H, Sampson Emily, Arrizabalaga Gustavo
Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA.
Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA.
bioRxiv. 2023 Jun 13:2023.06.13.544803. doi: 10.1101/2023.06.13.544803.
Apicomplexan parasites, including , encode many plant-like proteins, which play significant roles and present attractive targets for drug development. In this study, we have characterized the plant-like protein phosphatase PPKL, which is unique to the parasite and absent in its mammalian host. We have shown that its localization changes as the parasite divides. In non-dividing parasites, it is present in the cytoplasm, nucleus, and preconoidal region. As the parasite begins division, PPKL is enriched in the preconoidal region and the cortical cytoskeleton of the nascent parasites. Later in the division, PPKL is present in the basal complex ring. Conditional knockdown of PPKL showed that it is essential for parasite propagation. Moreover, parasites lacking PPKL exhibit uncoupling of division, with normal DNA duplication but severe defects in forming daughter parasites. While PPKL depletion does not impair the duplication of centrosomes, it affects the rigidity and arrangement of the cortical microtubules. Both Co-Immunoprecipitation and proximity labeling identified the kinase DYRK1 as a potential functional partner of PPKL. Complete knockout of phenocopies lack of PPKL, strongly suggesting a functional relationship between these two signaling proteins. Global phosphoproteomics analysis revealed a significant increase in phosphorylation of the microtubule-associated proteins SPM1 in PPKL-depleted parasites, suggesting PPKL regulates the cortical microtubules by mediating the phosphorylation state of SPM1. More importantly, the phosphorylation of cell cycle-associated kinase Crk1, a known regulator of daughter cell assembly, is altered in PPKL-depleted parasites. Thus, we propose that PPKL regulates daughter parasite development by influencing the Crk1-dependent signaling pathway.
顶复门寄生虫,包括……,编码许多植物样蛋白,这些蛋白发挥着重要作用,并且是药物开发的有吸引力的靶点。在本研究中,我们对寄生虫特有的、在其哺乳动物宿主中不存在的植物样蛋白磷酸酶PPKL进行了表征。我们已经表明,其定位随着寄生虫的分裂而变化。在不分裂的寄生虫中,它存在于细胞质、细胞核和前锥体区域。当寄生虫开始分裂时,PPKL在新生寄生虫的前锥体区域和皮质细胞骨架中富集。在分裂后期,PPKL存在于基部复合体环中。PPKL的条件性敲低表明它对寄生虫繁殖至关重要。此外,缺乏PPKL的寄生虫表现出分裂解偶联,DNA复制正常,但在形成子寄生虫方面存在严重缺陷。虽然PPKL的缺失不会损害中心体的复制,但它会影响皮质微管的刚性和排列。免疫共沉淀和邻近标记都确定激酶DYRK1是PPKL的潜在功能伙伴。……的完全敲除模拟了缺乏PPKL的情况,强烈表明这两种信号蛋白之间存在功能关系。全局磷酸蛋白质组学分析显示,在PPKL缺失的寄生虫中,微管相关蛋白SPM1的磷酸化显著增加,表明PPKL通过介导SPM1的磷酸化状态来调节皮质微管。更重要的是,细胞周期相关激酶Crk1(已知的子细胞组装调节因子)的磷酸化在PPKL缺失的寄生虫中发生了改变。因此,我们提出PPKL通过影响Crk1依赖性信号通路来调节子寄生虫的发育。