Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India.
PLoS Pathog. 2021 Nov 15;17(11):e1009595. doi: 10.1371/journal.ppat.1009595. eCollection 2021 Nov.
Tail-anchored (TA) proteins are defined by the absence of N-terminus signal sequence and the presence of a single transmembrane domain (TMD) proximal to their C-terminus. They play fundamental roles in cellular processes including vesicular trafficking, protein translocation and quality control. Some of the TA proteins are post-translationally integrated by the Guided Entry of TA (GET) pathway to the cellular membranes; with their N-terminus oriented towards the cytosol and C-terminus facing the organellar lumen. The TA repertoire and the GET machinery have been extensively characterized in the yeast and mammalian systems, however, they remain elusive in the human malaria parasite Plasmodium falciparum. In this study, we bioinformatically predicted a total of 63 TA proteins in the P. falciparum proteome and revealed the association of a subset with the P. falciparum homolog of Get3 (PfGet3). In addition, our proximity labelling studies either definitively identified or shortlisted the other eligible GET constituents, and our in vitro association studies validated associations between PfGet3 and the corresponding homologs of Get4 and Get2 in P. falciparum. Collectively, this study reveals the presence of proteins with hallmark TA signatures and the involvement of evolutionary conserved GET trafficking pathway for their targeted delivery within the parasite.
尾锚定(TA)蛋白的定义是缺乏 N 端信号序列,而在 C 端附近存在单一的跨膜结构域(TMD)。它们在包括囊泡运输、蛋白质易位和质量控制在内的细胞过程中发挥着基本作用。一些 TA 蛋白通过引导 TA(GET)途径被翻译后整合到细胞膜中;它们的 N 端朝向细胞质,C 端朝向细胞器腔。TA 库和 GET 机制在酵母和哺乳动物系统中得到了广泛的研究,然而,在人类疟原虫 Plasmodium falciparum 中,它们仍然难以捉摸。在这项研究中,我们通过生物信息学预测了 P. falciparum 蛋白质组中的总共 63 个 TA 蛋白,并揭示了其中一部分与 PfGet3(疟原虫 Get3 的同源物)相关联。此外,我们的邻近标记研究明确鉴定或确定了其他符合条件的 GET 成分,我们的体外关联研究验证了 PfGet3 与 PfGet4 和 PfGet2 的相应同源物之间的关联。总的来说,这项研究揭示了寄生虫内具有标志性 TA 特征的蛋白的存在,以及涉及进化保守的 GET 运输途径来靶向输送这些蛋白。