Kegawa Yuto, Male Frances, Jiménez-Munguía Irene, Blank Paul S, Mekhedov Elena, Ward Gary E, Zimmerberg Joshua
Section on Integrative Biophysics; Division of Basic and Translational Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, MD, USA.
Department of Microbiology and Molecular Genetics, University of Vermont Larner College of Medicine, Burlington, VT, USA.
EMBO Rep. 2025 Sep 19. doi: 10.1038/s44319-025-00565-8.
The parasite Toxoplasma gondii invades its host cell only after secreting proteins such as invasion-requisite RON2 that inserts into the host cell membrane to establish the moving junction. Electrophysiological recordings at sub-200 µs resolution show a transient increase in host cell membrane conductance following parasite exposure. Transients always precede invasion, but parasites depleted of RON2 generate transients without invading. Thus RON2 is not essential for transient generation. Time-series analysis developed here and applied to the 910,000 data point transient dataset reveal multiple quantal conductance changes in the parasite-induced transient, consistent with rapid insertion, then slower removal, blocking, or inactivation of potential pore components. Quantal steps for wild-type RH strain parasites have a principal mode with Gaussian mean of 0.26 nS, similar in step size to the pore forming protein EXP2, part of the PTEX translocon of malaria parasites. Without RON2 the quantal mean (0.19 nS) is significantly different. Because we observe no parasite invasion without poration, the term "invasion pore" is proposed to describe this transient breach in host cell membrane barrier integrity during invasion.
寄生虫刚地弓形虫仅在分泌诸如入侵必需的RON2等蛋白质后才侵入宿主细胞，RON2插入宿主细胞膜以建立移动连接。分辨率低于200微秒的电生理记录显示，寄生虫暴露后宿主细胞膜电导会短暂增加。瞬变现象总是先于入侵出现，但缺乏RON2的寄生虫会产生瞬变现象却不发生入侵。因此，RON2对于瞬变现象的产生并非必不可少。本文开发并应用于91万个数据点瞬变数据集的时间序列分析揭示，寄生虫诱导的瞬变过程中存在多个量子电导变化，这与潜在孔道成分的快速插入，随后较慢的移除、阻断或失活相一致。野生型RH株寄生虫的量子步长具有高斯均值为0.26纳安的主要模式，步长与疟原虫PTEX转位子的孔形成蛋白EXP2相似。缺乏RON2时，量子均值（0.19纳安）有显著差异。由于我们观察到没有孔形成就没有寄生虫入侵，因此提出“入侵孔”这一术语来描述入侵过程中宿主细胞膜屏障完整性的这种短暂破坏。
