Ng'ang'a Peter Njenga, Folz Julian, Kucher Svetlana, Roderer Daniel, Xu Ying, Sitsel Oleg, Belyy Alexander, Prumbaum Daniel, Kühnemuth Ralf, Assafa Tufa E, Dong Min, Seidel Claus A M, Bordignon Enrica, Raunser Stefan
Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany.
Chair of Molecular Physical Chemistry, Heinrich-Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany.
Sci Adv. 2025 Jan 3;11(1):eadr2019. doi: 10.1126/sciadv.adr2019.
Tc toxins are pore-forming virulence factors of many pathogenic bacteria. Following pH-induced conformational changes, they perforate the target membrane like a syringe to translocate toxic enzymes into a cell. Although this complex transformation has been structurally well studied, the reaction pathway and the resulting temporal evolution have remained elusive. We used an integrated biophysical approach to monitor prepore-to-pore transition and found a reaction time of ~30 hours for a complete transition. We show two asynchronous general steps of the process, shell opening and channel ejection, with the overall reaction pathway being a slow multistep process involving three intermediates. Liposomes, an increasingly high pH, or receptors facilitate shell opening, which is directly correlated with an increased rate of the prepore-to-pore transition. Channel ejection is a near-instantaneous process which occurs with a transition time of <60 milliseconds. Understanding the mechanism of action of Tc toxins and unveiling modulators of the kinetics are key steps toward their application as biomedical devices or biopesticides.
Tc毒素是许多病原菌的成孔毒力因子。在pH诱导的构象变化后，它们像注射器一样穿透靶膜，将毒性酶转运到细胞内。尽管这种复杂的转变在结构上已得到充分研究，但反应途径和由此产生的时间演变仍不清楚。我们采用综合生物物理方法监测前孔到孔的转变，发现完全转变的反应时间约为30小时。我们展示了该过程的两个异步一般步骤，即外壳打开和通道排出，整个反应途径是一个涉及三个中间体的缓慢多步过程。脂质体、越来越高的pH值或受体促进外壳打开，这与前孔到孔转变速率的增加直接相关。通道排出是一个几乎瞬间的过程，发生的转变时间小于60毫秒。了解Tc毒素的作用机制并揭示动力学调节剂是将其用作生物医学装置或生物杀虫剂的关键步骤。
