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Title | High-resolution structure of the Shigella type-III secretion needle by solid-state NMR and cryo-electron microscopy. |
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Journal, issue, pages | Nat Commun, Vol. 5, Page 4976, Year 2014 |
Publish date | Sep 29, 2014 |
![]() | Jean-Philippe Demers / Birgit Habenstein / Antoine Loquet / Suresh Kumar Vasa / Karin Giller / Stefan Becker / David Baker / Adam Lange / Nikolaos G Sgourakis / ![]() ![]() |
PubMed Abstract | We introduce a general hybrid approach for determining the structures of supramolecular assemblies. Cryo-electron microscopy (cryo-EM) data define the overall envelope of the assembly and rigid-body ...We introduce a general hybrid approach for determining the structures of supramolecular assemblies. Cryo-electron microscopy (cryo-EM) data define the overall envelope of the assembly and rigid-body orientation of the subunits while solid-state nuclear magnetic resonance (ssNMR) chemical shifts and distance constraints define the local secondary structure, protein fold and inter-subunit interactions. Finally, Rosetta structure calculations provide a general framework to integrate the different sources of structural information. Combining a 7.7-Å cryo-EM density map and 996 ssNMR distance constraints, the structure of the type-III secretion system needle of Shigella flexneri is determined to a precision of 0.4 Å. The calculated structures are cross-validated using an independent data set of 691 ssNMR constraints and scanning transmission electron microscopy measurements. The hybrid model resolves the conformation of the non-conserved N terminus, which occupies a protrusion in the cryo-EM density, and reveals conserved pore residues forming a continuous pattern of electrostatic interactions, thereby suggesting a mechanism for effector protein translocation. |
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Methods | NMR (solid-state) / EM (helical sym.) |
Resolution | 7.7 Å |
Structure data | ![]() PDB-2mme: |
Source |
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![]() | PROTEIN TRANSPORT / type-three secretion system / filamentous protein / helical assembly / Shigella flexneri / protein translocation / hybrid methods / Rosetta |