Download MendeleyStructure of the calcium-dependent type 2 secretion pseudopilus.
Lopez-Castilla, A., Thomassin, J.L., Bardiaux, B., Zheng, W., Nivaskumar, M., Yu, X., Nilges, M., Egelman, E.H., Izadi-Pruneyre, N., Francetic, O.(2017) Nat Microbiol 2: 1686-1695
- PubMed: 28993624
- DOI: https://doi.org/10.1038/s41564-017-0041-2
- Primary Citation of Related Structures:
5O2Y, 5WDA - PubMed Abstract:
Many Gram-negative bacteria use type 2 secretion systems (T2SSs) to secrete proteins involved in virulence and adaptation. Transport of folded proteins via T2SS nanomachines requires the assembly of inner membrane-anchored fibres called pseudopili. Although efficient pseudopilus assembly is essential for protein secretion, structure-based functional analyses are required to unravel the mechanistic link between these processes. Here, we report an atomic model for a T2SS pseudopilus from Klebsiella oxytoca, obtained by fitting the NMR structure of its calcium-bound subunit PulG into the ~5-Å-resolution cryo-electron microscopy reconstruction of assembled fibres. This structure reveals the comprehensive network of inter-subunit contacts and unexpected features, including a disordered central region of the PulG helical stem, and highly flexible C-terminal residues on the fibre surface. NMR, mutagenesis and functional analyses highlight the key role of calcium in PulG folding and stability. Fibre disassembly in the absence of calcium provides a basis for pseudopilus length control, essential for protein secretion, and supports the Archimedes screw model for the type 2 secretion mechanism.
Organizational Affiliation:
NMR of Biomolecules Unit, Department of Structural Biology and Chemistry, Institut Pasteur, CNRS UMR3528, 28 rue du Dr Roux, 75724, Paris, France.
