Arias Padilla Luisa F, Lopez Jonathan Munera, Shibata Aika, Murray John M, Hu Ke
bioRxiv. 2024 Jul 16:2024.07.14.603470. doi: 10.1101/2024.07.14.603470.
The human parasite has a distinctive body plan with a well-defined polarity. In the apical complex, the minus ends of the 22 cortical microtubules are anchored to the apical polar ring, a putative microtubule-organizing center. The basal complex caps and constricts the parasite posterior end, and is critical for cytokinesis. How this apical-basal polarity axis is initiated was unknown. Here we examined the development of the apical polar ring and the basal complex in nascent daughters using expansion microscopy. We found that different substructures in the apical polar ring have different sensitivity to stress. In addition, apical-basal differentiation is already established upon nucleation of the cortical microtubule array: arc forms of the apical polar ring and basal complex associate with opposite ends of the microtubules. As the construction of the daughter framework progresses towards the centrioles, the apical and the basal arcs co-develop in striking synchrony ahead of the microtubule array, and close into a ring-form before all the microtubules are nucleated. We also found that two apical polar ring components, APR2 and KinesinA, act synergistically. The removal of each protein individually has modest to no impact on the lytic cycle. However, the loss of both results in abnormalities in the microtubule array and highly reduced plaquing and invasion efficiency.
这种人体寄生虫具有独特的身体结构，具有明确的极性。在顶复合体中，22条皮质微管的负端锚定在顶极环上，顶极环是一个假定的微管组织中心。基部复合体覆盖并收缩寄生虫的后端，对胞质分裂至关重要。这种顶-基极性轴是如何启动的尚不清楚。在这里，我们使用扩展显微镜检查了新生子代中顶极环和基部复合体的发育情况。我们发现顶极环中的不同亚结构对压力有不同的敏感性。此外，在皮质微管阵列成核时，顶-基分化就已经建立：顶极环和基部复合体的弧形与微管的相对两端相关联。随着子代框架向中心粒方向构建，顶弧和基弧在微管阵列之前显著同步共同发育，并在所有微管成核之前闭合形成环形。我们还发现顶极环的两个组成部分，APR2和驱动蛋白A，协同发挥作用。单独去除每种蛋白质对裂解周期的影响不大或没有影响。然而，两者都缺失会导致微管阵列异常，以及噬斑形成和侵袭效率大幅降低。
