一种顶端蛋白 Pcr2 对于人类寄生虫刚地弓形虫的持续运动是必需的。

An apical protein, Pcr2, is required for persistent movement by the human parasite Toxoplasma gondii.

机构信息

Biodesign Center for Mechanisms of Evolution/School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America.

Department of Biology, Indiana University, Bloomington, Indiana, United States of America.

出版信息

PLoS Pathog. 2022 Aug 22;18(8):e1010776. doi: 10.1371/journal.ppat.1010776. eCollection 2022 Aug.

Abstract

The phylum Apicomplexa includes thousands of species of unicellular parasites that cause a wide range of human and animal diseases such as malaria and toxoplasmosis. To infect, the parasite must first initiate active movement to disseminate through tissue and invade into a host cell, and then cease moving once inside. The parasite moves by gliding on a surface, propelled by an internal cortical actomyosin-based motility apparatus. One of the most effective invaders in Apicomplexa is Toxoplasma gondii, which can infect any nucleated cell and any warm-blooded animal. During invasion, the parasite first makes contact with the host cell "head-on" with the apical complex, which features an elaborate cytoskeletal apparatus and associated structures. Here we report the identification and characterization of a new component of the apical complex, Preconoidal region protein 2 (Pcr2). Pcr2 knockout parasites replicate normally, but they are severely diminished in their capacity for host tissue destruction due to significantly impaired invasion and egress, two vital steps in the lytic cycle. When stimulated for calcium-induced egress, Pcr2 knockout parasites become active, and secrete effectors to lyse the host cell. Calcium-induced secretion of the major adhesin, MIC2, also appears to be normal. However, the movement of the Pcr2 knockout parasite is spasmodic, which drastically compromises egress. In addition to faulty motility, the ability of the Pcr2 knockout parasite to assemble the moving junction is impaired. Both defects likely contribute to the poor efficiency of invasion. Interestingly, actomyosin activity, as indicated by the motion of mEmerald tagged actin chromobody, appears to be largely unperturbed by the loss of Pcr2, raising the possibility that Pcr2 may act downstream of or in parallel with the actomyosin machinery.

摘要

肉足鞭毛门包括数千种单细胞寄生虫,这些寄生虫可引起广泛的人类和动物疾病,如疟疾和弓形体病。为了感染,寄生虫必须首先开始主动运动,通过组织传播并侵入宿主细胞,然后一旦进入细胞内就停止运动。寄生虫通过在表面滑行来运动,由内部皮质肌动球蛋白为基础的运动装置推动。在肉足鞭毛门中最有效的入侵体之一是刚地弓形虫,它可以感染任何有核细胞和任何温血动物。在入侵过程中,寄生虫首先用顶复合器与宿主细胞“正面接触”,顶复合器具有精细的细胞骨架装置和相关结构。在这里,我们报告了顶复合器的一个新成分,即前锥区蛋白 2(Pcr2)的鉴定和特征。Pcr2 敲除寄生虫正常复制,但由于入侵和逸出能力严重受损,它们在破坏宿主组织的能力大大降低,这是裂解周期中的两个重要步骤。当受到钙诱导逸出的刺激时,Pcr2 敲除寄生虫变得活跃,并分泌效应子裂解宿主细胞。主要黏附素 MIC2 的钙诱导分泌似乎也正常。然而,Pcr2 敲除寄生虫的运动是痉挛性的,这极大地损害了逸出。除了运动缺陷外,Pcr2 敲除寄生虫组装运动连接的能力也受损。这两个缺陷可能都导致入侵效率低下。有趣的是,肌动球蛋白活性,如 mEmerald 标记的肌动蛋白染色质体的运动所表明的,似乎在很大程度上不受 Pcr2 缺失的影响,这增加了 Pcr2 可能在肌动球蛋白机制下游或平行起作用的可能性。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/2538/9436145/085769daf29f/ppat.1010776.g001.jpg

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