5WDA

Structure of the PulG pseudopilus

Summary for 5WDA

• Entry DOI: 10.2210/pdb5wda/pdb
• Related: 5O2Y
• EMDB information: 8812
• Descriptor: General secretion pathway protein G, CALCIUM ION (2 entities in total)
• Functional Keywords: helical polymer, bacterial secretion, cryo-em, protein transport
• Biological source: Klebsiella oxytoca
• Total number of polymer chains: 25
• Total formula weight: 364139.00

Authors

Lopez-Castilla, A.,Thomassin, J.L.,Bardiaux, B.,Zheng, W.,Nivaskumar, M.,Yu, X.,Nilges, M.,Egelman, E.H.,Izadi-Pruneyre, N.,Francetic, O. (deposition date: 2017-07-04, release date: 2017-10-25, Last modification date: 2024-10-16)

Primary citation

Lopez-Castilla, A.,Thomassin, J.L.,Bardiaux, B.,Zheng, W.,Nivaskumar, M.,Yu, X.,Nilges, M.,Egelman, E.H.,Izadi-Pruneyre, N.,Francetic, O.
Structure of the calcium-dependent type 2 secretion pseudopilus.
Nat Microbiol, 2:1686-1695, 2017

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.

PubMed: 28993624
DOI: 10.1038/s41564-017-0041-2

Experimental method

ELECTRON MICROSCOPY (5 Å)