9H80

Structure of the outer membrane exopolysaccharide transporter PelBC

Summary for 9H80

• Entry DOI: 10.2210/pdb9h80/pdb
• EMDB information: 51916
• Descriptor: PelB, PelC, PHOSPHATIDYLETHANOLAMINE (3 entities in total)
• Functional Keywords: exopolysaccharide, complex, acyl-chain, transport protein
• Biological source: Pseudomonas aeruginosa; More
• Total number of polymer chains: 13
• Total formula weight: 379410.09

Authors

Benedens, M.,Rosales, C.,Beckmann, R.,Kedrov, A. (deposition date: 2024-10-28, release date: 2025-06-11, Last modification date: 2025-06-18)

Primary citation

Benedens, M.,Rosales-Hernandez, C.,Straathof, S.A.P.,Loschwitz, J.,Berninghausen, O.,Maglia, G.,Beckmann, R.,Kedrov, A.
Assembly and the gating mechanism of the Pel exopolysaccharide export complex PelBC of Pseudomonas aeruginosa.
Nat Commun, 16:5249-5249, 2025

PubMed Abstract: The pathogen Pseudomonas aeruginosa enhances its virulence and antibiotic resistance upon formation of durable biofilms. The exopolysaccharides Pel, Psl and alginate essentially contribute to the biofilm matrix, but their secretion mechanisms are barely understood. Here, we reveal the architecture of the outer membrane complex PelBC for Pel export, where the essential periplasmic ring of twelve lipoproteins PelC is mounted on top of the nanodisc-embedded β-barrel PelB. The PelC assembly is stabilized by electrostatic contacts with the periplasmic rim of PelB and via the membrane-anchored acyl chains. The negatively charged interior of the PelB β-barrel forms a route for the cationic Pel exopolysaccharide. The β-barrel is sealed at the extracellular side, but molecular dynamic simulations suggest that the short loop Plug-S is sufficiently flexible to open a tunnel for the exopolysaccharide transport. This gating model is corroborated by single-channel conductivity measurements, where a deletion of Plug-S renders a constitutively open β-barrel. Our structural and functional analysis offers a comprehensive view on this pathogenicity-relevant complex and suggests the route taken by the exopolysaccharide at the final secretion step.

PubMed: 40473691
DOI: 10.1038/s41467-025-60605-8

Experimental method

ELECTRON MICROSCOPY (2.5 Å)