9GBC

Bacteroides thetaiotaomicron siderophore transporter XusA in complex with surface-exposed lipoprotein XusB

Summary for 9GBC

• Entry DOI: 10.2210/pdb9gbc/pdb
• Related: 9GAR
• EMDB information: 51210
• Descriptor: TonB-linked outer membrane receptor, DUF4374 domain-containing protein (3 entities in total)
• Functional Keywords: outer membrane, membrane protein complex, siderophore transport, iron piracy, metal transport
• Biological source: Bacteroides thetaiotaomicron VPI-5482; More
• Total number of polymer chains: 2
• Total formula weight: 140941.59

Authors

Silale, A.,van den Berg, B. (deposition date: 2024-07-30, release date: 2025-08-06, Last modification date: 2025-09-17)

Primary citation

Silale, A.,Soo, Y.L.,Mark, H.,Motz, R.N.,Basle, A.,Nolan, E.M.,van den Berg, B.
Structural basis of iron piracy by human gut Bacteroides.
Biorxiv, 2025

PubMed Abstract: Iron is an essential element that can be growth-limiting in microbial communities, particularly those present within host organisms. To acquire iron, many bacteria secrete siderophores, secondary metabolites that chelate ferric iron. These iron chelates can be transported back into the cell via TonB-dependent transporters in the outer membrane, followed by intracellular liberation of the iron. Pathogenic and produce siderophores during gut infection. In response to iron starvation, the human gut symbiont upregulates an iron piracy system, XusABC, which steals iron-bound siderophores from the invading pathogens. Here, we investigated the molecular details of xenosiderophore uptake across the outer membrane by the XusAB complex. Our crystal and cryogenic electron microscopy structures explain how the XusB lipoprotein recognises iron-bound xenosiderophores and passes them on to the XusA TonB-dependent transporter. Moreover, we show that Xus homologues can transport a variety of siderophores with different iron-chelating functional groups.

PubMed: 40894706
DOI: 10.1101/2024.04.15.589501

Experimental method

ELECTRON MICROSCOPY (2.7 Å)