Download MendeleyStepwise firing mechanism of an extracellular contractile injection system.
Xu, J., Ericson, C.F., Toenshoff, E.R., Pilhofer, M.(2026) Nat Commun
- PubMed: 42031783 Search on PubMed
- DOI: https://doi.org/10.1038/s41467-026-72240-y
- Primary Citation Related Structures:
9WSZ, 9WT0, 9WT1 - PubMed Abstract:
Contractile injection systems (CISs) mediate cell-cell interactions and are widespread among bacteria and archaea. These phage tail-like macromolecular machines puncture their target by a tube that is propelled by a contractile sheath. The mechanism underlying CIS firing, which starts with target binding and ends with sheath contraction, remains unclear. Here, we investigate the extracellular CIS from Algoriphagus machipongonensis (AlgoCIS) by a multimodal cryo-electron microscopy approach and structure-guided engineering, which allowed us to arrest AlgoCIS in multiple intermediate states of firing. Together with the post-firing structure, our data suggest a stepwise firing mechanism involving all structural modules: signal propagation starts with the binding of the tail-fibers, followed by opening of the cage, an expansion of the baseplate iris, and resulting in sheath contraction and the release of cap adaptor. Our study will serve as a framework for understanding the firing mechanism of diverse CISs and will facilitate the engineering of CISs for biomedical applications.
- Department of Biology, Institute of Molecular Biology & Biophysics, Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland. jingwei.xu@westlake.edu.cn.
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