EMD-17575

Single-particle
2.97 Å
EMD-17575 Deposition: 05/06/2023
Map released: 16/08/2023
Last modified: 20/09/2023
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-17575

BtuB3G3 bound to cyanocobalamin with ordered EL8

EMD-17575

Single-particle
2.97 Å
EMD-17575 Deposition: 05/06/2023
Map released: 16/08/2023
Last modified: 20/09/2023
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Bacteroides thetaiotaomicron VPI-5482
Sample: Complex of TonB-dependent transporter BtuB3 with surface lipoprotein BtuG3 bound to cyanocobalamin (state 1)
Fitted models: 8p98 (Avg. Q-score: 0.506)

Deposition Authors: Silale A , Abellon-Ruiz J , van den Berg B
BtuB TonB-dependent transporters and BtuG surface lipoproteins form stable complexes for vitamin B 12 uptake in gut Bacteroides.
Abellon-Ruiz J , Jana K, Silale A , Frey AM , Basle A, Trost M, Kleinekathofer U , van den Berg B
(2023) Nat Commun , 14 , 4714 - 4714
PUBMED: 37543597
DOI: doi:10.1038/s41467-023-40427-2
ISSN: 2041-1723
Abstract:
Vitamin B12 (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 B12 outer membrane transporters together with a conserved array of surface-exposed B12-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 B12 with high affinities. Closing of the BtuG lid following B12 capture causes destabilisation of the bound B12 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.