8P97

BtuB3G3 bound to cyanocobalamin with disordered EL8

Summary for 8P97

• Entry DOI: 10.2210/pdb8p97/pdb
• EMDB information: 17574
• Descriptor: TonB-dependent receptor, Putative surface layer protein, CYANOCOBALAMIN (3 entities in total)
• Functional Keywords: cyanocobalamin, transporter, lipoprotein, complex, membrane protein
• Biological source: Bacteroides thetaiotaomicron VPI-5482; More
• Total number of polymer chains: 2
• Total formula weight: 121412.78

Authors

Silale, A.,Abellon-Ruiz, J.,van den Berg, B. (deposition date: 2023-06-05, release date: 2023-08-16, Last modification date: 2023-09-20)

Primary citation

Abellon-Ruiz, J.,Jana, K.,Silale, A.,Frey, A.M.,Basle, A.,Trost, M.,Kleinekathofer, U.,van den Berg, B.
BtuB TonB-dependent transporters and BtuG surface lipoproteins form stable complexes for vitamin B 12 uptake in gut Bacteroides.
Nat Commun, 14:4714-4714, 2023

PubMed Abstract: Vitamin B (cobalamin) is required for most human gut microbes, many of which are dependent on scavenging to obtain this vitamin. Since bacterial densities in the gut are extremely high, competition for this keystone micronutrient is severe. Contrasting with Enterobacteria, members of the dominant genus Bacteroides often encode several BtuB vitamin B outer membrane transporters together with a conserved array of surface-exposed B-binding lipoproteins. Here we show that the BtuB transporters from Bacteroides thetaiotaomicron form stable, pedal bin-like complexes with surface-exposed BtuG lipoprotein lids, which bind B with high affinities. Closing of the BtuG lid following B capture causes destabilisation of the bound B by a conserved BtuB extracellular loop, causing translocation of the vitamin to BtuB and subsequent transport. We propose that TonB-dependent, lipoprotein-assisted small molecule uptake is a general feature of Bacteroides spp. that is important for the success of this genus in colonising the human gut.

PubMed: 37543597
DOI: 10.1038/s41467-023-40427-2

Experimental method

ELECTRON MICROSCOPY (2.75 Å)