In situ architecture, function, and evolution of a contractile injection system
By Désirée Böck, J. Medeiros, Han-Fei Tsao, T. Penz, G. L. Weiss, Karin Aistleitner, M. Horn, M. Pilhofer. 2017
142 citations recorded by the source corpus.
Identification of a new injection system To interact with other cells, bacteria use contractile machines that function similarly to membrane-puncturing bacteriophages. The so-called type 6 secretion system (T6SS) functions from inside a bacterial cell. Böck et al. used modern electron microscopy methods and functional assays to resolve the structure and function of a T6SS in the cellular context. They identified three modules and showed large-scale structural changes upon firing. T6SSs are organized in multibarrel gun-like arrays and may contribute to the survival of bacteria inside their host. Science, this issue p. 713 A model type 6 secretion system reveals the structure, dynamics, and evolution of apparatus attachment to the target membrane. Contractile injection systems mediate bacterial cell-cell interactions by a bacteriophage tail–like structure. In contrast to extracellular systems, the type 6 secretion system (T6SS) is defined by intracellular localization and attachment to the cytoplasmic membrane. Here we used cryo-focused ion beam milling, electron cryotomography, and functional assays to study a T6SS in Amoebophilus asiaticus. The in situ architecture revealed three modules, including a contractile sheath-tube, a baseplate, and an anchor. All modules showed conformational changes upon firing. Lateral baseplate interactions coordinated T6SSs in hexagonal arrays. The system mediated interactions with host membranes and may participate in phagosome escape. Evolutionary sequence analyses predicted that T6SSs are more widespread than previously thought. Our insights form the basis for understanding T6SS key concepts and exploring T6SS diversity.
Subfields: Ecology, Endocrinology, Genetics
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Citations in the corpus
- Protein Injection Machines in Bacteria (2018, unknown): “Although Hcp is required for the assembly of the extended sheath, the contracted sheath can still form in the absence of other T6SS components (Brackmann et al., 2017).”
- Contractile injection systems of bacteriophages and related systems (2018, background): “Likewise, the production of a contractile injection system (e.g., T6SS) is a great expenditure of energy and material for a bacterium and its activation and triggering should be tightly regulated (Brackmann et al., 2017).”