High-resolution structure of a Shigella type III secretion needle by solid-state NMR and cryo-electron microscopy

By J. Demers, Birgit Habenstein, A. Loquet, S. Vasa, Karin Giller, S. Becker, David Baker, A. Lange, Nikolaos G. Sgourakis. 2014

111 citations recorded by the source corpus.

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. Solving structures of large protein complexes remains a significant challenge for structural biologists. Demers et al. determine the atomic structure of a Shigellatype-III secretion system using a Rosetta-based modelling strategy that draws on both solid-state NMR and cryo-electron microscopy data sets.

Subfields: Atomic and Molecular Physics, and Optics, Nuclear and High Energy Physics, Spectroscopy

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Citations in the corpus

Integrative protein modeling in RosettaNMR from sparse paramagnetic restraints (2019, unknown): “…Integrative Modeling Platform (IMP) (Russel et al., 2012), or BCL::Fold (Weiner et al., 2014) are pioneering applications that integrate information from multiple biophysical and biochemical sources and have led to structures of complex protein systems (Demers et al., 2014; Robinson et al., 2015).”
Bacterial Secretion Systems – An overview (2016, background): “The T3SS needle has an inner hollow core that is wide enough to permit an unfolded effector to traverse (60, 61).”