Projects per year
Abstract
Type III secretion systems are found in many Gram-negative bacteria. They are activated by contact with eukaryotic cells and inject virulence proteins inside them. Host cell detection requires a protein complex located at the tip of the device's external injection needle. The tip complex (TC) is composed of IpaD, a hydrophilic protein, and IpaB, a hydrophobic protein, which later forms part of the injection pore in the host membrane. Here we used labelling and crosslinking methods to show that TCs from a ΔipaB strain contain 5 IpaD subunits while the TCs from wild-type can also contain 1 IpaB and 4 IpaD subunits. Electron microscopy followed by single particle and helical image analysis was used to reconstruct three-dimensional images of TCs at ∼20 Å resolution. Docking of an IpaD crystal structure, constrained by the crosslinks observed, reveals TC organisation is different from that of all previously proposed models. Our findings suggest new mechanisms for tip complex assembly and function. The tip complex is the only site within these secretion systems targeted by disease-protecting antibodies. By suggesting how these act, our work will allow improvement of prophylactic and therapeutic strategies.
Original language | English |
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Pages (from-to) | 31-50 |
Journal | Molecular Microbiology |
Volume | 95 |
DOIs | |
Publication status | Published - 29 Oct 2014 |
Bibliographical note
This article is protected by copyright. All rights reserved.Research Groups and Themes
- Engineering Mathematics Research Group
- Bristol BioDesign Institute
Keywords
- synthetic biology
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Dive into the research topics of 'Three-dimensional electron microscopy reconstruction and cysteine-mediated crosslinking provide a model of the T3SS needle tip complex'. Together they form a unique fingerprint.Projects
- 2 Finished
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Bacterial type III secretion systems: from structure to function
Blocker, A. J. (Principal Investigator)
28/01/12 → 28/05/15
Project: Research
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Datasets
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Electron microscopy 3DR of T3SS needle tip complex
Kato, T. (Creator), Blocker, A. (Creator), Makino, F. (Creator), Cheung, M. (Creator) & Fernando, V. (Creator), University of Bristol, 29 Oct 2014
DOI: 10.5523/bris.1trtuj35bwn5410ibhinps47ag, http://data.bris.ac.uk/data/dataset/1trtuj35bwn5410ibhinps47ag
Dataset