Biodesign Center for Mechanisms of Evolution/School of Life Sciences, Arizona State University, Tempe, AZ 85284, USA.
Department of Biology, Indiana University, Bloomington, ID 47405, USA.
J Cell Sci. 2023 Sep 1;136(17). doi: 10.1242/jcs.261270. Epub 2023 Sep 7.
Motility is essential for apicomplexan parasites to infect their hosts. In a three-dimensional (3D) environment, the apicomplexan parasite Toxoplasma gondii moves along a helical path. The cortical microtubules, which are ultra-stable and spirally arranged, have been considered to be a structure that guides the long-distance movement of the parasite. Here, we address the role of the cortical microtubules in parasite motility, invasion and egress by utilizing a previously generated mutant (dubbed 'TKO') in which these microtubules are destabilized in mature parasites. We found that the cortical microtubules in ∼80% of the non-dividing (i.e. daughter-free) TKO parasites are much shorter than normal. The extent of depolymerization was further exacerbated upon commencement of daughter formation or cold treatment, but parasite replication was not affected. In a 3D Matrigel matrix, the TKO mutant moved directionally over long distances, but along trajectories that were significantly more linear (i.e. less helical) than those of wild-type parasites. Interestingly, this change in trajectory did not impact either movement speed in the matrix or the speed and behavior of the parasite during entry into and egress from the host cell.
运动性对于顶复门寄生虫感染宿主至关重要。在三维（3D）环境中，顶复门寄生虫刚地弓形虫沿螺旋路径移动。皮质微管超稳定且呈螺旋排列，被认为是指导寄生虫远距离运动的结构。在这里，我们通过利用先前生成的突变体（称为“TKO”）来解决皮质微管在寄生虫运动性、入侵和出芽中的作用，在成熟寄生虫中，这些微管不稳定。我们发现，在大约 80%的不分裂（即无子代）的 TKO 寄生虫中，皮质微管比正常情况下短得多。在开始形成子代或冷处理时，解聚程度进一步加剧，但寄生虫复制不受影响。在 3D Matrigel 基质中，TKO 突变体能够长距离定向移动，但轨迹明显比野生型寄生虫更直（即更不螺旋）。有趣的是，这种轨迹的变化既不会影响基质中的运动速度，也不会影响寄生虫进入和离开宿主细胞时的速度和行为。
