9GZR

Tad pilus alignment complex protein RcpC

Summary for 9GZR

• Entry DOI: 10.2210/pdb9gzr/pdb
• EMDB information: 51732
• Descriptor: RcpC (1 entity in total)
• Functional Keywords: tad pilus, pseudomonas aeruginosa, membrane protein, biofilms
• Biological source: Pseudomonas aeruginosa PAO1
• Total number of polymer chains: 12
• Total formula weight: 357802.72

Authors

Evans, S.L.,Peretiazhko, I.,Bergeron, J.R.C. (deposition date: 2024-10-04, release date: 2025-05-21, Last modification date: 2025-08-13)

Primary citation

Evans, S.L.,Peretiazhko, I.,Karnani, S.Y.,Marmont, L.S.,Wheeler, J.H.R.,Tseng, B.S.,Durham, W.M.,Whitney, J.C.,Bergeron, J.R.C.
The structure of the Tad pilus alignment complex reveals a periplasmic conduit for pilus extension.
Nat Commun, 16:6977-6977, 2025

PubMed Abstract: The Tad (Tight adherence) pilus is a bacterial appendage implicated in virulence, cell-cell aggregation, and biofilm formation. Despite its homology to the well-characterised Type IV pilus, the structure and assembly mechanism of the Tad pilus are poorly understood. Here, we investigate the role of the Tad pilus protein RcpC from Pseudomonas aeruginosa. Our analyses reveal that RcpC forms a dodecameric periplasmic complex, anchored to the inner membrane by a transmembrane helix, and interacting with the outer membrane secretin RcpA. We use single-particle Cryo-EM to elucidate the structure of the RcpC dodecamer, and cell-based assays to demonstrate that the RcpC-RcpA complex is essential for Tad-mediated cell-cell aggregation. Collectively, these data demonstrate that RcpC forms the Tad pilus alignment complex, which provides a conduit across the periplasm for the Tad pilus filament to access the extracellular milieu. Our experimental data and structure-based model allow us to propose a mechanism for Tad plus assembly.

PubMed: 40730569
DOI: 10.1038/s41467-025-62457-8

Experimental method

ELECTRON MICROSCOPY (2.45 Å)